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>

src/xmpp/roster.c

@@ -201,7 +201,7 @@ roster_set_handler(xmpp_stanza_t* const stanza)
 
     // if from attribute exists and it is not current users barejid, ignore push
     const char* from = xmpp_stanza_get_from(stanza);
-    if (from && (strcmp(from, connection_get_barejid()) != 0)) {
+    if (!equals_our_barejid(from)) {
         log_warning("Received alleged roster push from: %s", from);
         return;
     }