fix tiny memory leak in read_packet (leak only happens when malloc returns NULL so it's very rare)

Signed-off-by: Julien Danjou <julien@danjou.info>

src/xcb_in.c

@@ -191,6 +191,7 @@ static int read_packet(xcb_connection_t *c)
         if(!cur)
         {
             _xcb_conn_shutdown(c);
+            free(buf);
             return 0;
         }
         cur->reply = buf;