Add support for wl_keyboard::keymap events

These keymap events communicate the keymap from the compositor to the
clients via fd passing, rather than having the clients separately
compile a map.

Signed-off-by: Daniel Stone <daniel@fooishbar.org>
diff --git a/src/compositor.h b/src/compositor.h
index 23beb5f..d070471 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -164,6 +164,9 @@
 
 struct weston_xkb_info {
 	struct xkb_keymap *keymap;
+	int keymap_fd;
+	size_t keymap_size;
+	char *keymap_area;
 	xkb_mod_index_t ctrl_mod;
 	xkb_mod_index_t alt_mod;
 	xkb_mod_index_t super_mod;