Import v1.5.20
Merge tag 'v1.5.20'

Import v1.5.20

Conflicts:
	Makefile.in
	aclocal.m4
	cdemo/configure
	configure
	demo/configure
	doc/Makefile.in
	doc/libtool.info
	doc/stamp-vti
	doc/version.texi
	libltdl/Makefile.am
	libltdl/Makefile.in
	libltdl/aclocal.m4
	libltdl/configure
	libltdl/ltmain.sh
	ltmain.in
	ltmain.sh
	tests/Makefile.in

Reverted a couple of patches in ltmain.in, ltmain.sh and libltdl/ltmain.sh
that are almost certainly only of historical interest (Digital UNIX ksh).

Reverted all built files to vendor versions (we have a long way to go getting
upto date and don't want to spend time merging them only to regenerate at the
end).