The URI for namespaced docbook-xsl was updated to reflect the current
DocBook upstream at <https://cdn.docbook.org/>.
libstdc++-v3/Changelog:
* acinclude.m4: Update docbook xsl URI.
* configure: Regenerate.
dnl
AC_DEFUN([GLIBCXX_CONFIGURE_DOCBOOK], [
-glibcxx_docbook_url=http://docbook.sourceforge.net/release/xsl-ns/current/
+glibcxx_docbook_url=http://cdn.docbook.org/release/xsl/current/
AC_MSG_CHECKING([for local stylesheet directory])
glibcxx_local_stylesheets=no
-glibcxx_docbook_url=http://docbook.sourceforge.net/release/xsl-ns/current/
+glibcxx_docbook_url=http://cdn.docbook.org/release/xsl/current/
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for local stylesheet directory" >&5
$as_echo_n "checking for local stylesheet directory... " >&6; }