Introduce equals_our_barejid()

Instead of always repeating the same pattern, introduce a helper function.

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

tests/unittests/xmpp/stub_xmpp.c

@@ -75,6 +75,12 @@ connection_get_barejid(void)
     return mock_ptr_type(char*);
 }
 
+gboolean
+equals_our_barejid(const char* cmp)
+{
+    return TRUE;
+}
+
 char*
 connection_get_user(void)
 {