* configure.in: Rename to configure.ac.

	* configure.ac: Renamed from configure.in; make minimum necessary
	changes for autoconf 2.5x.
	* aclocal.m4: Make minimum necessary changes for autoconf 2.5x.
	* configure: Regenerate with autoconf 2.57.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@75362 138bc75d-0d04-0410-961f-82ee72b054a4