PR ada/6637, PR ada/5911

	Merge with libada-branch:
	* configure.in, Makefile.tpl, Makefile.def: Add target-libada,
	with appropriate dependencies. Add --enable-libada configure switch.
	* configure, Makefile.in: Regenerate.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@77594 138bc75d-0d04-0410-961f-82ee72b054a4