try to fix a problem with valgrind. applied memory leak fix from Brent

* Makefile.am doc/examples/Makefile.am python/tests/Makefile.am
  xstc/Makefile.am: try to fix a problem with valgrind.
* python/generator.py python/libxml.c python/tests/Makefile.am
  python/tests/tstmem.py: applied memory leak fix from Brent Hendricks
  c.f. bug #165349
Daniel

python/tests/Makefile.am

@@ -37,7 +37,8 @@ PYTESTS=	\
     sync.py \
     tstLastError.py \
     indexes.py \
-    dtdvalid.py
+    dtdvalid.py \
+    tstmem.py
 
 XMLS=		\
     tst.xml	\

python/tests/tstmem.py

@@ -0,0 +1,36 @@
+#!/usr/bin/python -u
+import libxml2
+import libxml2mod
+import sys
+
+def error(msg, data):
+    pass
+
+# Memory debug specific
+libxml2.debugMemory(1)
+
+dtd="""<!ELEMENT foo EMPTY>"""
+instance="""<?xml version="1.0"?>
+<foo></foo>"""
+
+dtd = libxml2.parseDTD(None, 'test.dtd')
+ctxt = libxml2.newValidCtxt()
+libxml2mod.xmlSetValidErrors(ctxt._o, error, error)
+doc = libxml2.parseDoc(instance)
+ret = doc.validateDtd(ctxt, dtd)
+if ret != 1:
+    print "error doing DTD validation"
+    sys.exit(1)
+
+doc.freeDoc()
+dtd.freeDtd()
+del dtd
+del ctxt
+
+# Memory debug specific
+libxml2.cleanupParser()
+if libxml2.debugMemory(1) == 0:
+    print "OK"
+else:
+    print "Memory leak %d bytes" % (libxml2.debugMemory(1))
+    libxml2.dumpMemory()