memory: Remove memory debugging

This is useless compared to sanitizers or valgrind and has a
considerable performance impact if enabled accidentally.

parser.c

@@ -685,11 +685,7 @@ xmlHasFeature(xmlFeature feature)
             return(0);
 #endif
         case XML_WITH_DEBUG_MEM:
-#ifdef DEBUG_MEMORY_LOCATION
-            return(1);
-#else
             return(0);
-#endif
         case XML_WITH_ZLIB:
 #ifdef LIBXML_ZLIB_ENABLED
             return(1);