update libtool.m4 in src

[DJ Delorie]

"ltconfig; ltmain.sh; ltcf-*.sh
	libtool: http://www.gnu.org/software/libtool/
	Changes need to be done in tandem with the official LIBTOOL
	sources or submitted to the master file maintainer and brought
	in via a merge."

So, permission is implied if it's in the upstream repository.  Enjoy.

As for the individual subdirs (other than the configure regenerates,
which are included with the above implied permission), you'll have to
take it up with the individual projects.  RDA is gdb, sid is its own
thing.

http://sourceware.org/rda/
http://sourceware.org/sid/