Hardcoded "-nocache" in Buildsystem/qmake.pm

From this bug https://bugreports.qt-project.org/browse/QTCREATORBUG-9840?focusedCommentId=210535&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-210535

Problem with build qtcreator 2.8.0 with -nocache specified. Because qtcreator is "unfair" recursive qmake project.

In my PPA i rewrote debian/rules like:

#!/usr/bin/make -f

# Uncomment this to turn on verbose mode.
# export DH_VERBOSE=1

CPPFLAGS:=$(shell dpkg-buildflags --get CPPFLAGS)
CFLAGS:=$(shell dpkg-buildflags --get CFLAGS) $(CPPFLAGS)
CXXFLAGS:=$(shell dpkg-buildflags --get CXXFLAGS) $(CPPFLAGS)
LDFLAGS:=$(shell dpkg-buildflags --get LDFLAGS)
export CPPFLAGS CFLAGS CXXFLAGS LDFLAGS

DEB_HOST_MULTIARCH ?= $(shell dpkg-architecture -qDEB_HOST_MULTIARCH)

# Upstream changelog
upstream_changes := $(wildcard dist/changes-*)

%:
        dh $@ --parallel --list-missing --dbg-package=qtcreator-dbg --buildsystem=qmake_qt4 --builddirectory=builddir

override_dh_auto_configure:
        mkdir -p builddir
        cd builddir && qmake -makefile "IDE_LIBRARY_BASENAME=lib/$(DEB_HOST_MULTIARCH)" IDE_PACKAGE_MODE=1 USE_SYSTEM_BOTAN=1 "QMAKE_CFLAGS_RELEASE=${CFLAGS} ${CPPFLAGS}" "QMAKE_CXXFLAGS_RELEASE=${CXXFLAGS} ${CPPFLAGS}" "QMAKE_LFLAGS_RELEASE=${LDFLAGS}" "QMAKE_STRIP=:" "PREFIX=/usr" "../qtcreator.pro" -r

override_dh_auto_install:
ifneq (,$(filter qtcreator-doc, $(shell dh_listpackages)))
        dh_auto_build -- qch_docs
endif
        dh_auto_install --destdir=debian/tmp/usr
        dh_auto_build -- install_docs INSTALL_ROOT=$(CURDIR)/debian/tmp/usr

override_dh_auto_clean:
        dh_auto_clean

override_dh_installdocs:
        dh_installdocs -pqtcreator $(upstream_changes)
        dh_installdocs --remaining-packages

override_dh_makeshlibs:
        # qtcreator doesn't provide any public libraries

override_dh_builddeb:
        dh_builddeb -- -Zxz