gnat.exp: Handle multilib.

testsuite/
2009-04-06  Laurent GUERBY  <laurent@guerby.net>

        * lib/gnat.exp: Handle multilib.
        
libada/
2009-04-06  Laurent GUERBY  <laurent@guerby.net>

        * Makefile.in (ADA_RTS_DIR): Define.
        * Makefile.in (gnatlib-*): Link adainclude and adalib to it.

From-SVN: r145622