weston-terminal: Fix crash on first keystroke

Since 894b3rcc634 weston-terminal will crash on first keystroke if you
fail to create an xkb compose state.  This can happen if you don't have
a Compose file.

Instead, now we just return uncomposed symbols.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>

clients/window.c

@@ -3108,6 +3108,8 @@ static xkb_keysym_t
 process_key_press(xkb_keysym_t sym, struct input *input)
 {
 #ifdef HAVE_XKBCOMMON_COMPOSE
+	if (!input->xkb.compose_state)
+		return sym;
 	if (sym == XKB_KEY_NoSymbol)
 		return sym;
 	if (xkb_compose_state_feed(input->xkb.compose_state,