cleaning up XPath error reporting that time. applied the two patches for

* error.c include/libxml/xmlerror.h include/libxml/xpath.h
  include/libxml/xpathInternals.h xpath.c: cleaning up XPath
  error reporting that time.
* threads.c: applied the two patches for TLS threads
  on Windows from Jesse Pelton
* parser.c: tiny safety patch for xmlStrPrintf() make sure the
  return is always zero terminated. Should also help detecting
  passing wrong buffer size easilly.
* result/VC/* result/valid/rss.xml.err result/valid/xlink.xml.err:
  updated the results to follow the errors string generated by
  last commit.
Daniel

parser.c

@@ -2449,6 +2449,7 @@ xmlStrPrintf(xmlChar *buf, int len, const xmlChar *msg, ...) {
     va_start(args, msg);
     ret = vsnprintf((char *) buf, len, (const char *) msg, args);
     va_end(args);
+    buf[len - 1] = 0; /* be safe ! */
     
     return(ret);
 }