attempt to work around what seemed a gcc optimizer bug when handling

* xpath.c: attempt to work around what seemed a gcc optimizer
  bug when handling floats on i386 http://veillard.com/gcc.bug
* tree.c entities.c encoding.c: doing some cleanups while
  chasing it
Daniel
diff --git a/tree.c b/tree.c
index ae97e7c..3316d25 100644
--- a/tree.c
+++ b/tree.c
@@ -5645,12 +5645,12 @@
 #endif
 	return;
     }
-    if (doc == NULL) {
 #ifdef DEBUG_TREE
+    if (doc == NULL) {
         xmlGenericError(xmlGenericErrorContext,
 		"xmlElemDump : doc == NULL\n");
-#endif
     }
+#endif
     buf = xmlBufferCreate();
     if (buf == NULL) return;
     if ((doc != NULL) &&