Remove the direct azure dependencies from gfx, layout and layout_thread.

This does not cover transitive dependencies through canvas_traits, though that
should not be too hard to solve either.

components/gfx/lib.rs

@@ -18,7 +18,6 @@
 
 extern crate alloc;
 extern crate app_units;
-extern crate azure;
 #[allow(unused_extern_crates)]
 #[macro_use]
 extern crate bitflags;