libweston: rename weston_output_destroy() to weston_output_release()

'release' is a more appropriate name because the function does not free
the underlying memory. The main reason for this is that we need the name
weston_output_destroy() for new API that actually will free also the
underlying memory.

Since the function is only used in backends and external backends are
not a thing, this does not cause libweston major version bump, even
though it does change the ABI. There is no way external users could have
successfully used this function.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Ian Ray <ian.ray@ge.com>
Acked-by Daniel Stone <daniels@collabora.com>
diff --git a/libweston/compositor-wayland.c b/libweston/compositor-wayland.c
index e8639a0..26cfdd5 100644
--- a/libweston/compositor-wayland.c
+++ b/libweston/compositor-wayland.c
@@ -703,7 +703,7 @@
 
 	wayland_output_disable(&output->base);
 
-	weston_output_destroy(&output->base);
+	weston_output_release(&output->base);
 
 	if (output->frame_cb)
 		wl_callback_destroy(output->frame_cb);
@@ -1376,7 +1376,7 @@
 	return 0;
 
 out:
-	weston_output_destroy(&output->base);
+	weston_output_release(&output->base);
 	free(output->title);
 	free(output);
 
@@ -1424,7 +1424,7 @@
 err_set_size:
 	wayland_backend_destroy_output_surface(output);
 err_surface:
-	weston_output_destroy(&output->base);
+	weston_output_release(&output->base);
 	free(output->title);
 	free(output);