scripts/internals: do not remove lib{32,64}/ symlinks after build

During the build, we create lib{32,64}/ symlinks out of the sysroot.
In some cases (eg. mingw32 target), these symlinks are still required
when running the toolchain. For other combinations, the symlinks are
without incidence, so they can be safely kept after the build.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 # powerpc specific configuration file

 ## select ARCH_SUPPORTS_32

 ## select ARCH_SUPPORTS_64 if EXPERIMENTAL

 ## select ARCH_DEFAULT_32

 ## select ARCH_USE_MMU

 ## select ARCH_SUPPORT_ABI

 ## select ARCH_SUPPORT_CPU

 ## select ARCH_SUPPORT_TUNE

 ##

 ## help The PowerPC architecture, as defined by:

 ## help     http://www.ibm.com/developerworks/eserver/articles/archguide.html