apply a couple of patches from Christian Cornelssen fixing the man pages

* libxml.3 doc/buildDocBookCatalog: apply a couple of patches
  from Christian Cornelssen fixing the man pages and the Catalog
  building script.
* xmlschemas.c include/libxml/schemasInternals.h: nothing new yet
  next step is <xs:import> I now have a reasonable understanding
  of how it works.
Daniel
diff --git a/doc/buildDocBookCatalog b/doc/buildDocBookCatalog
index 513796a..bf51ace 100755
--- a/doc/buildDocBookCatalog
+++ b/doc/buildDocBookCatalog
@@ -5,7 +5,7 @@
     mkdir /etc/xml
     chmod 755 /etc/xml
 fi
-if [ -w /etc/xml/catalog -a -w /etc/xml ]
+if [ -w /etc/xml/catalog ] || [ -w /etc/xml -a ! -e /etc/xml/catalog ]
 then
     ROOTCATALOG=/etc/xml/catalog
     CATALOG=/etc/xml/docbook