Certain broken versions of xsltproc ignore the --nonet option and will
attempt to fetch the docbook stylesheet from the WWW when it isn't in
the local XML catalog.

This patch checks for the local stylesheet directory first, and doesn't
use xsltproc if no local stylesheets are found. Checking for the local
directory is done using xmlcatalog if available, only checking the
hardcoded list of directories if xmlcatalog fails. The right directory
for Suse is added to the hardcoded list.

This should avoid doing an xsltproc check that would need to download
the stylesheet, so no network connection is made even if a broken
xsltproc is present.

	PR libstdc++/89466
	* acinclude.m4 (GLIBCXX_CONFIGURE_DOCBOOK): Reorder check for local
	stylesheet directories before check for xsltproc. Try to use
	xmlcatalog to find local stylesheet directory before trying hardcoded
	paths. Add path used by suse to hardcoded paths. Adjust xsltproc
	check to look for the same stylesheet as doc/Makefile.am uses. Don't
	use xsltproc if xmlcatalog fails to find a local stylesheet.
	* configure.ac: Check for xmlcatalog.
	* Makefile.in: Regenerate.
	* configure: Likewise.
	* doc/Makefile.in: Likewise.
	* include/Makefile.in: Likewise.
	* libsupc++/Makefile.in: Likewise.
	* po/Makefile.in: Likewise.
	* python/Makefile.in: Likewise.
	* src/Makefile.in: Likewise.
	* src/c++11/Makefile.in: Likewise.
	* src/c++17/Makefile.in: Likewise.
	* src/c++98/Makefile.in: Likewise.
	* src/filesystem/Makefile.in: Likewise.
	* testsuite/Makefile.in: Likewise.

From-SVN: r269249