Fix installation of 32bit libraries after r288074.

Fix installation of 32bit libraries after r288074.

FILES is not used when LIBRARIES_ONLY is set, which is used to build and
install the lib32 sysroot.  All of the csu files do quality as "libraries"
for this case so just undefine LIBRARIES_ONLY.

This is still better than the previous realinstall handling as it does
not hook into META_MODE properly.

Sponsored by:	EMC / Isilon Storage Division