Makefile.in (s-mlib): New argument MULTILIB_REUSE.

2013-01-13  Terry Guo  <terry.guo@arm.com>

        * gcc/Makefile.in (s-mlib): New argument MULTILIB_REUSE.
        * gcc/doc/fragments.texi: Document MULTILIB_REUSE.
        * gcc/gcc.c (multilib_reuse): New internal spec.
        (set_multilib_dir): Also search multilib from multilib_reuse.
        * gcc/genmultilib (tmpmultilib3): Refactor code.
        (tmpmultilib4): Ditto.
        (multilib_reuse): New multilib argument.

From-SVN: r195134