fsnotify: switch send_to_group() and ->handle_event to const struct qstr *

note that conditions surrounding accesses to dname in audit_watch_handle_event()
and audit_mark_handle_event() guarantee that dname won't have been NULL.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 7eb7821..c28f6ed 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -117,7 +117,7 @@
 	int (*handle_event)(struct fsnotify_group *group,
 			    struct inode *inode,
 			    u32 mask, const void *data, int data_type,
-			    const unsigned char *file_name, u32 cookie,
+			    const struct qstr *file_name, u32 cookie,
 			    struct fsnotify_iter_info *iter_info);
 	void (*free_group_priv)(struct fsnotify_group *group);
 	void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);