make logging functions private

Fixes #189

Signed-off-by: Steffen Jaeckel <jaeckel-floss@eyet-services.de>

src/parser_libxml2.c

@@ -140,7 +140,8 @@ static void _start_element(void *userdata,
         if (!parser->stanza && parser->depth != 1) {
             /* something terrible happened */
             /* FIXME: we should probably trigger a disconnect */
-            xmpp_error(parser->ctx, "parser", "oops, where did our stanza go?");
+            strophe_error(parser->ctx, "parser",
+                          "oops, where did our stanza go?");
         } else if (!parser->stanza) {
             /* starting a new toplevel stanza */
             parser->stanza = xmpp_stanza_new(parser->ctx);