[cross] fix multi-arch field for lib*-dev

this patch obsoletes previous one and takes care of libstdc++ and libobjc as well.

This bug was fixed in the package gcc-4.7 - 4.7.2-5ubuntu2

---------------
gcc-4.7 (4.7.2-5ubuntu2) raring; urgency=low

  * Merge with Debian.

gcc-4.7 (4.7.2-5) UNRELEASED; urgency=low

  * Update to SVN 20121025 (r192803) from the gcc-4_7-branch.
    - Fix PR target/54892 (ARM, LP: #1065122), PR rtl-optimization/54870,
      PR rtl-optimization/53701, PR target/53975 (ia64),
      PR tree-optimization/54902 (LP: #1065559), PR middle-end/54945.

  [ Matthias Klose ]
  * Update the Linaro support to the 4.7-2012.10 release.
  * Define MULTIARCH_DIRNAME for arm64 (Wookey).
  * Let the lib*objc-dev packages depend on the lib*gcc-dev packages.
  * Let the libstdc++-dev package depend on the libgcc-dev package.
  * Drop the dependency of the libstdc++-dev package on g++, make
    libstdc++-dev and libstdc++-pic Multi-Arch: same. Closes: #678623.
  * Install override files before calling dh_fixperms.
  * Backport the libffi arm64 port.
  * Build libx32gcc-dev, libx32objc-dev and libx32gfortran-dev packages.
  * Allow conditional building of the x32 multilibs.
  * Fix libmudflap build failure for x32 multilibs.
  * Fix dependency on glibc for triarch builds.
  * Add build-{arch,indep} targets.
  * Fix libquadmath x32 multilib builds on kernels which don't support x32.
  * Fix location of x32 specific C++ header files.

  [ Thibaut Girka ]
  * Split out lib*gcc-dev packages.
  * Split out lib*objc-dev packages.
  * Split out lib*gfortran-dev packages.

  [ Daniel Schepler ]
  * Add support for x32. Closes: #667005.
  * New patch hjl-x32-gcc-4_7-branch.diff to incorporate changes from
    that branch, including --with-abi=mx32 option.

  [ Marcin Juszkiewicz ]
  * lib*-dev packages for cross builds are not Multi-Arch: same. LP: #1070694.
 -- Matthias Klose <email address hidden> Thu, 25 Oct 2012 13:31:07 +0200