cosmetic: replace boolean function return values with bool

For functions that test if something is true/valid and return a 1
or 0, it makes sense to switch to bool.

Reviewed-by: Bryce Harrington <b.harrington@samsung.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/src/input.c b/src/input.c
index 1c71b2c..b504d06 100644
--- a/src/input.c
+++ b/src/input.c
@@ -1732,7 +1732,7 @@
 	keyboard_release
 };
 
-static int
+static bool
 should_send_modifiers_to_client(struct weston_seat *seat,
 				struct wl_client *client)
 {
@@ -1740,15 +1740,15 @@
 	    seat->keyboard->focus &&
 	    seat->keyboard->focus->resource &&
 	    wl_resource_get_client(seat->keyboard->focus->resource) == client)
-		return 1;
+		return true;
 
 	if (seat->pointer &&
 	    seat->pointer->focus &&
 	    seat->pointer->focus->surface->resource &&
 	    wl_resource_get_client(seat->pointer->focus->surface->resource) == client)
-		return 1;
+		return true;
 
-	return 0;
+	return false;
 }
 
 static void