scripts: always create lib32 and lib64 symlinks

Unconditionally create the lib32 -> lib/ and lib64 -> lib/ symlinks.

This is reportedly a fix to build a toolchain for a 32-bit target on
a 'pure' 64-bit host (eg. on Fedora FC12, host libs are in lib64/,
and there is no lib -> lib64 symlink, as we can see on other distors,
as Debian). As gcc only puts static host lib in lib64/ (along with
target files in subdirs), we can safely create the symlinks.

Also note that the symlinks are summarily removed at the end
of the build.

Signed-off-by: Anthony Foiani <anthony.foiani@gmail.com>
[Yann E. MORIN: fix a comment, rephrase the commit log]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 # s390 specific config options

 # depends on EXPERIMENTAL

 config ARCH_s390

     select ARCH_SUPPORTS_32

     select ARCH_SUPPORTS_64

     select ARCH_DEFAULT_32

     select ARCH_USE_MMU

     select ARCH_SUPPORT_FPU

     help

       Defined by IBM in:

         32-bit ESA/390       : http://publibfp.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/dz9ar008/CCONTENTS

         64-bit z/Architecure : http://publibfp.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/dz9zr002/CCONTENTS