Add a weston_surface_set_size function

Surfaces that are created by clients get their size automatically updated
by the attach/commit.  Surfaces created directly by shells (such as black
surfaces) sometimes need to be manually resized.  This function allows you
to do that while being somewhat less messy than messing with the internals
of weston_surface manually.

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
diff --git a/src/compositor.h b/src/compositor.h
index f5a0ba4..f32a497 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -1152,6 +1152,10 @@
 int
 weston_surface_is_mapped(struct weston_surface *surface);
 
+WL_EXPORT void
+weston_surface_set_size(struct weston_surface *surface,
+			int32_t width, int32_t height);
+
 void
 weston_surface_schedule_repaint(struct weston_surface *surface);