gqueue: Remove a redundant branch
gqueue: Remove a redundant branch

queue->tail->next cannot be non-NULL, as pushing onto the end of the
queue is handled by the call to g_queue_push_tail_link() above.

Signed-off-by: Philip Withnall <29c2a2ac2a854b9cf047275aa9de346d096be2e0@endlessm.com>

endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib