chat: fix segfault when checking origin

strcmp(3) segfaulted when comparing the from address to NULL.

Checking messages originated from the output account only makes sense
with groupchat. Remove the check for type of "chat".

src/xmppipe.c

@@ -1071,9 +1071,7 @@ handle_message(xmpp_conn_t * const conn, xmpp_stanza_t * const stanza,
         return 1;
 
     /* Check if the message is from us */
-    if (XMPPIPE_STREQ(type,
-          state->opt & XMPPIPE_OPT_GROUPCHAT ? "groupchat" : "chat")
-        && XMPPIPE_STREQ(from, state->mucjid))
+    if (XMPPIPE_STREQ(type, "groupchat") && XMPPIPE_STREQ(from, state->mucjid))
         return 1;
 
     child = xmpp_stanza_get_child_by_name(stanza, "body");