Header not found when building ubuntu_bpf on Bionic s390x/ppc64el/arm64

It looks like these build error are not fatal, it's just complaining about some missing headers:

Steps:
1. git clone --depth=1 https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/bionic
2. cd bionic/testing/selftests/bpf
3. make

Results:
Issue complained when compiling:
* test_pkt_access.c
* test_xdp.c
* test_l4lb.c
* test_tcp_estats.c
* test_obj_id.c
* test_pkt_md_access.c
* test_xdp_redirect.c
* test_xdp_meta.c
* sockmap_parse_prog.c
* sockmap_verdict_prog.c
* dev_cgroup.c

clang -I. -I./include/uapi -I../../../include/uapi \
  -Wno-compare-distinct-pointer-types \
  -O2 -target bpf -emit-llvm -c /home/ubuntu/bionic/tools/testing/selftests/bpf/test_pkt_access.c -o - | \
llc -march=bpf -mcpu=generic -filetype=obj -o /home/ubuntu/bionic/tools/testing/selftests/bpf/test_pkt_access.o
In file included from /home/ubuntu/bionic/tools/testing/selftests/bpf/test_pkt_access.c:8:
/usr/include/string.h:26:10: fatal error: 'bits/libc-header-start.h' file not found
#include <bits/libc-header-start.h>
         ^~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
clang -I. -I./include/uapi -I../../../include/uapi \
  -Wno-compare-distinct-pointer-types \
  -O2 -target bpf -emit-llvm -c /home/ubuntu/bionic/tools/testing/selftests/bpf/test_xdp.c -o - | \
llc -march=bpf -mcpu=generic -filetype=obj -o /home/ubuntu/bionic/tools/testing/selftests/bpf/test_xdp.o
In file included from /home/ubuntu/bionic/tools/testing/selftests/bpf/test_xdp.c:8:
/usr/include/string.h:26:10: fatal error: 'bits/libc-header-start.h' file not found
#include <bits/libc-header-start.h>
         ^~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
clang -I. -I./include/uapi -I../../../include/uapi \
  -Wno-compare-distinct-pointer-types \
  -O2 -target bpf -emit-llvm -c /home/ubuntu/bionic/tools/testing/selftests/bpf/test_l4lb.c -o - | \
llc -march=bpf -mcpu=generic -filetype=obj -o /home/ubuntu/bionic/tools/testing/selftests/bpf/test_l4lb.o
In file included from /home/ubuntu/bionic/tools/testing/selftests/bpf/test_l4lb.c:9:
/usr/include/string.h:26:10: fatal error: 'bits/libc-header-start.h' file not found
#include <bits/libc-header-start.h>
         ^~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
clang -I. -I./include/uapi -I../../../include/uapi \
  -Wno-compare-distinct-pointer-types \
  -O2 -target bpf -emit-llvm -c /home/ubuntu/bionic/tools/testing/selftests/bpf/test_tcp_estats.c -o - | \
llc -march=bpf -mcpu=generic -filetype=obj -o /home/ubuntu/bionic/tools/testing/selftests/bpf/test_tcp_estats.o
In file included from /home/ubuntu/bionic/tools/testing/selftests/bpf/test_tcp_estats.c:34:
/usr/include/string.h:26:10: fatal error: 'bits/libc-header-start.h' file not found
#include <bits/libc-header-start.h>
         ^~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
clang -I. -I./include/uapi -I../../../include/uapi \
  -Wno-compare-distinct-pointer-types \
  -O2 -target bpf -emit-llvm -c /home/ubuntu/bionic/tools/testing/selftests/bpf/test_obj_id.c -o - | \
llc -march=bpf -mcpu=generic -filetype=obj -o /home/ubuntu/bionic/tools/testing/selftests/bpf/test_obj_id.o
In file included from /home/ubuntu/bionic/tools/testing/selftests/bpf/test_obj_id.c:8:
In file included from ../../../include/uapi/linux/bpf.h:11:
In file included from ./include/uapi/linux/types.h:5:
/usr/include/asm-generic/int-ll64.h:12:10: fatal error: 'asm/bitsperlong.h' file not found
#include <asm/bitsperlong.h>
         ^~~~~~~~~~~~~~~~~~~
1 error generated.
clang -I. -I./include/uapi -I../../../include/uapi \
  -Wno-compare-distinct-pointer-types \
  -O2 -target bpf -emit-llvm -c /home/ubuntu/bionic/tools/testing/selftests/bpf/test_pkt_md_access.c -o - | \
llc -march=bpf -mcpu=generic -filetype=obj -o /home/ubuntu/bionic/tools/testing/selftests/bpf/test_pkt_md_access.o
In file included from /home/ubuntu/bionic/tools/testing/selftests/bpf/test_pkt_md_access.c:8:
/usr/include/string.h:26:10: fatal error: 'bits/libc-header-start.h' file not found
#include <bits/libc-header-start.h>
         ^~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
clang -I. -I./include/uapi -I../../../include/uapi \
  -Wno-compare-distinct-pointer-types \
  -O2 -target bpf -emit-llvm -c /home/ubuntu/bionic/tools/testing/selftests/bpf/test_xdp_redirect.c -o - | \
llc -march=bpf -mcpu=generic -filetype=obj -o /home/ubuntu/bionic/tools/testing/selftests/bpf/test_xdp_redirect.o
In file included from /home/ubuntu/bionic/tools/testing/selftests/bpf/test_xdp_redirect.c:12:
In file included from ../../../include/uapi/linux/bpf.h:11:
In file included from ./include/uapi/linux/types.h:5:
/usr/include/asm-generic/int-ll64.h:12:10: fatal error: 'asm/bitsperlong.h' file not found
#include <asm/bitsperlong.h>
         ^~~~~~~~~~~~~~~~~~~
1 error generated.
clang -I. -I./include/uapi -I../../../include/uapi \
  -Wno-compare-distinct-pointer-types \
  -O2 -target bpf -emit-llvm -c /home/ubuntu/bionic/tools/testing/selftests/bpf/test_xdp_meta.c -o - | \
llc -march=bpf -mcpu=generic -filetype=obj -o /home/ubuntu/bionic/tools/testing/selftests/bpf/test_xdp_meta.o
In file included from /home/ubuntu/bionic/tools/testing/selftests/bpf/test_xdp_meta.c:1:
In file included from ../../../include/uapi/linux/bpf.h:11:
In file included from ./include/uapi/linux/types.h:5:
/usr/include/asm-generic/int-ll64.h:12:10: fatal error: 'asm/bitsperlong.h' file not found
#include <asm/bitsperlong.h>
         ^~~~~~~~~~~~~~~~~~~
1 error generated.
clang -I. -I./include/uapi -I../../../include/uapi \
  -Wno-compare-distinct-pointer-types \
  -O2 -target bpf -emit-llvm -c /home/ubuntu/bionic/tools/testing/selftests/bpf/sockmap_parse_prog.c -o - | \
llc -march=bpf -mcpu=generic -filetype=obj -o /home/ubuntu/bionic/tools/testing/selftests/bpf/sockmap_parse_prog.o
In file included from /home/ubuntu/bionic/tools/testing/selftests/bpf/sockmap_parse_prog.c:1:
In file included from ../../../include/uapi/linux/bpf.h:11:
In file included from ./include/uapi/linux/types.h:5:
/usr/include/asm-generic/int-ll64.h:12:10: fatal error: 'asm/bitsperlong.h' file not found
#include <asm/bitsperlong.h>
         ^~~~~~~~~~~~~~~~~~~
1 error generated.
clang -I. -I./include/uapi -I../../../include/uapi \
  -Wno-compare-distinct-pointer-types \
  -O2 -target bpf -emit-llvm -c /home/ubuntu/bionic/tools/testing/selftests/bpf/sockmap_verdict_prog.c -o - | \
llc -march=bpf -mcpu=generic -filetype=obj -o /home/ubuntu/bionic/tools/testing/selftests/bpf/sockmap_verdict_prog.o
In file included from /home/ubuntu/bionic/tools/testing/selftests/bpf/sockmap_verdict_prog.c:1:
In file included from ../../../include/uapi/linux/bpf.h:11:
In file included from ./include/uapi/linux/types.h:5:
/usr/include/asm-generic/int-ll64.h:12:10: fatal error: 'asm/bitsperlong.h' file not found
#include <asm/bitsperlong.h>
         ^~~~~~~~~~~~~~~~~~~
1 error generated.
clang -I. -I./include/uapi -I../../../include/uapi \
  -Wno-compare-distinct-pointer-types \
  -O2 -target bpf -emit-llvm -c /home/ubuntu/bionic/tools/testing/selftests/bpf/dev_cgroup.c -o - | \
llc -march=bpf -mcpu=generic -filetype=obj -o /home/ubuntu/bionic/tools/testing/selftests/bpf/dev_cgroup.o
In file included from /home/ubuntu/bionic/tools/testing/selftests/bpf/dev_cgroup.c:8:
In file included from ../../../include/uapi/linux/bpf.h:11:
In file included from ./include/uapi/linux/types.h:5:
/usr/include/asm-generic/int-ll64.h:12:10: fatal error: 'asm/bitsperlong.h' file not found
#include <asm/bitsperlong.h>
         ^~~~~~~~~~~~~~~~~~~
1 error generated.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-4.15.0-33-generic 4.15.0-33.36
ProcVersionSignature: Ubuntu 4.15.0-33.36-generic 4.15.18
Uname: Linux 4.15.0-33-generic s390x
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
AlsaDevices: Error: command ['ls', '-l', '/dev/snd/'] failed with exit code 2: ls: cannot access '/dev/snd/': No such file or directory
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay': 'aplay'
ApportVersion: 2.20.9-0ubuntu7.3
Architecture: s390x
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord': 'arecord'
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
CurrentDmesg:

Date: Thu Aug 23 06:54:58 2018
HibernationDevice: RESUME=UUID=e2735dd1-cbbc-4424-9c25-d37d073d9414
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig': 'iwconfig'
Lsusb: Error: command ['lsusb'] failed with exit code 1:
PciMultimedia:

ProcFB: Error: [Errno 2] No such file or directory: '/proc/fb'
ProcKernelCmdLine: root=UUID=38f7d570-2973-4055-b668-12a9ace1e0c7 crashkernel=196M audit=0 BOOT_IMAGE=0
RelatedPackageVersions:
 linux-restricted-modules-4.15.0-33-generic N/A
 linux-backports-modules-4.15.0-33-generic N/A
 linux-firmware 1.173.1
RfKill: Error: [Errno 2] No such file or directory: 'rfkill': 'rfkill'
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)