Rename weston_compositor_xkb_init to weston_compositor_set_xkb_rule_names

weston_compositor_xkb_destroy() is called automatically so having only
weston_compositor_xkb_init() to be called by the user was a bit weird.
So rename it so that it makes more sense.
Also export it, since libweston compositors need to call it.

Signed-off-by: Giulio Camuffo <giuliocamuffo@gmail.com>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/src/input.c b/src/input.c
index 8fe898c..08378d1 100644
--- a/src/input.c
+++ b/src/input.c
@@ -2277,9 +2277,9 @@
 }
 
 #ifdef ENABLE_XKBCOMMON
-int
-weston_compositor_xkb_init(struct weston_compositor *ec,
-			   struct xkb_rule_names *names)
+WL_EXPORT int
+weston_compositor_set_xkb_rule_names(struct weston_compositor *ec,
+				     struct xkb_rule_names *names)
 {
 	ec->use_xkbcommon = 1;
 
@@ -2442,9 +2442,9 @@
 	return 0;
 }
 #else
-int
-weston_compositor_xkb_init(struct weston_compositor *ec,
-			   struct xkb_rule_names *names)
+WL_EXPORT int
+weston_compositor_set_xkb_rule_names(struct weston_compositor *ec,
+				     struct xkb_rule_names *names)
 {
 	return 0;
 }