Mark bookmarks() as safe

It isn't dangerous, helps people that use those features in playlists,
although those playlists are VLC-specific
(cherry picked from commit 3310dccd85dbe3c0ba8048c5236507c91d8a0e29)
Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

src/libvlc-module.c

@@ -1851,6 +1851,7 @@ vlc_module_begin ()
 
     add_string( "bookmarks", NULL, NULL,
                  BOOKMARKS_TEXT, BOOKMARKS_LONGTEXT, true )
+        change_safe ()
 
     set_section( N_( "Default devices") , NULL )