add xmlMemDisplayLast to help debug incremental memory leaks, and some

* include/libxml/xmlmemory.h xmlmemory.c: add xmlMemDisplayLast to
  help debug incremental memory leaks, and some cleanups
* runxmlconf.c: use that new call and avoid ever touching the
  system catalog in the regression tests
Daniel

svn path=/trunk/; revision=3760
4 files changed