Add keymap argument to weston_seat_init_keyboard

This allows backends to generate their own keymaps and pass them in for
use rather than always forcing a single global keymap, which is
particularly useful for nested compositors.

Signed-off-by: Daniel Stone <daniel@fooishbar.org>
diff --git a/src/compositor.h b/src/compositor.h
index f0dbddc..693b723 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -646,7 +646,7 @@
 void
 weston_seat_init_pointer(struct weston_seat *seat);
 void
-weston_seat_init_keyboard(struct weston_seat *seat);
+weston_seat_init_keyboard(struct weston_seat *seat, struct xkb_keymap *keymap);
 void
 weston_seat_init_touch(struct weston_seat *seat);