refs: pass gitdir to packed_ref_store_create

This is consistent with the calling convention for ref backend creation, and
avoids storing ".git/packed-refs" (the name of a regular file) in a variable called
ref_store::gitdir.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/refs/packed-backend.h b/refs/packed-backend.h
index f61a73e..9dd8a34 100644
--- a/refs/packed-backend.h
+++ b/refs/packed-backend.h
@@ -14,7 +14,7 @@ struct ref_transaction;
  */
 
 struct ref_store *packed_ref_store_create(struct repository *repo,
-					  const char *path,
+					  const char *gitdir,
 					  unsigned int store_flags);
 
 /*