Upgrade to libxml 2.9.2 and libxslt 1.1.28

third_party/libxml/patches/xmlregexp-bogus-cast

-Change bogus '(unsigned long)' cast to '(unsigned short)'
-
-Index: libxml/xmlregexp.c
-===================================================================
---- libxml.orig/xmlregexp.c     2010-07-09 14:16:36.990430641 -0700
-+++ libxml/xmlregexp.c  2010-07-09 14:16:40.939742007 -0700
-@@ -6470,7 +6470,7 @@
-     if (name != NULL) {
-        value += 30 * (*name);
-        while ((ch = *name++) != 0) {
--           value = value ^ ((value << 5) + (value >> 3) + (unsigned long)ch);
-+           value = value ^ ((value << 5) + (value >> 3) + (unsigned short)ch);
-        }
-     }
-     return (value);