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>

# MIPS specific config options

config ARCH_mips

    select ARCH_SUPPORTS_32

    select ARCH_SUPPORTS_64 if EXPERIMENTAL

    select ARCH_DEFAULT_32

    select ARCH_USE_MMU

    select ARCH_SUPPORTS_BOTH_ENDIAN

    select ARCH_DEFAULT_BE

    select ARCH_SUPPORT_ARCH

    select ARCH_SUPPORT_TUNE

    help

      The MIPS architecture, as defined by:

        http://www.mips.com/