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>

 # Menu for the native GDB

 config GDB_NATIVE

     bool

     prompt "Native gdb"

     default n

     depends on ! BARE_METAL

     depends on ! BACKEND

     help

       Build and install a native gdb for the target, to run on the target.

 if GDB_NATIVE

 config GDB_NATIVE_NO_STATIC

     bool

     default n

 config GDB_NATIVE_STATIC

     bool

     prompt "Build a static native gdb"

     depends on ! GDB_NATIVE_NO_STATIC

     default n

     help

       In case you have trouble with dynamic loading of shared libraries,

       you will find that a static gdb comes in handy.

 endif # GDB_NATIVE