mm: export lru_cache_add_*() to modules

This is needed to enable moving pages into the page cache in fuse with
splice(..., SPLICE_F_MOVE).
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

mm/swap.c

@@ -224,6 +224,7 @@ void __lru_cache_add(struct page *page, enum lru_list lru)
 		____pagevec_lru_add(pvec, lru);
 	put_cpu_var(lru_add_pvecs);
 }
+EXPORT_SYMBOL(__lru_cache_add);
 
 /**
  * lru_cache_add_lru - add a page to a page list