Add Valgrind to CI

* Also pass `$*` to `configure` when invoking `ci-build.sh`, so one can
  e.g. run `./ci-build.sh --without-xscreensaver`

Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>

src/xmpp/chat_session.c

@@ -89,7 +89,7 @@ void
 chat_sessions_clear(void)
 {
     if (sessions) {
-        g_hash_table_remove_all(sessions);
+        g_hash_table_destroy(sessions);
         sessions = NULL;
     }
 }