feat: Add stbbr_for_presence_to for MUC join presence matching

- Add prime_for_presence_to() and prime_get_for_presence_to() in prime.c
- Add presence_to_callback() in server.c to handle MUC join presence
- Export stbbr_for_presence_to() in stabber.h
- Add stanzas_debug_last() for debugging failed verifications

src/server/stanza.c

@@ -299,9 +299,7 @@ stanza_parse(char *stanza_text)
     XML_Parse(parser, stanza_text, strlen(stanza_text), 0);
     XML_ParserFree(parser);
 
-    XMPPStanza *result = state->curr_stanza;
-    free(state);
-    return result;
+    return state->curr_stanza;
 }
 
 static void

src/server/verify.c

@@ -63,7 +63,6 @@ verify_any(char *stanza_text, gboolean ign_timeout)
             usleep(1000 * 50);
             elapsed = g_timer_elapsed(timer, NULL);
         }
-        g_timer_destroy(timer);
     }
 
     if (result) {
@@ -95,7 +94,6 @@ verify_last(char *stanza_text)
             usleep(1000 * 50);
             elapsed = g_timer_elapsed(timer, NULL);
         }
-        g_timer_destroy(timer);
     }
 
     if (result) {