mm: Export migrate_page_move_mapping and migrate_page_copy

Export these symbols such that UBIFS can implement
->migratepage.

Cc: stable@vger.kernel.org
Signed-off-by: NRichard Weinberger <richard@nod.at>
Acked-by: NChristoph Hellwig <hch@lst.de>

mm/migrate.c

@@ -431,6 +431,7 @@ int migrate_page_move_mapping(struct address_space *mapping,
 
 	return MIGRATEPAGE_SUCCESS;
 }
+EXPORT_SYMBOL(migrate_page_move_mapping);
 
 /*
  * The expected number of remaining references is the same as that
@@ -586,6 +587,7 @@ void migrate_page_copy(struct page *newpage, struct page *page)
 
 	mem_cgroup_migrate(page, newpage);
 }
+EXPORT_SYMBOL(migrate_page_copy);
 
 /************************************************************
  *                    Migration functions