Leftover "Expand failed" debug output
This was originally reported at https://bugs.php.net/bug.php?id=70309 and apparently patched for our Windows builds, but never made it upstream, so I'm reporting it now. In https://gitlab.gnome.org/GNOME/libxml2/blob/master/xmlreader.c#L989 there's a leftover debug printf that probably shouldn't be there.