move duplicated ref_newer() to remote.c

ref_newer() appears to have been copied from builtin-send-pack.c to
http-push.c via cut and paste. This patch moves the function and its
helper unmark_and_free() to remote.c. There was a slight difference
between the two implementations, one used TMP_MARK for the mark, the
other used 1. Per Jeff King, I went with TMP_MARK as more correct.

This is in preparation for being able to call it from builtin-remote.c

Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/remote.h b/remote.h
index 56ca8b1..c0666a0 100644
--- a/remote.h
+++ b/remote.h
@@ -74,6 +74,7 @@ int check_ref_type(const struct ref *ref, int flags);
 void free_refs(struct ref *ref);
 
 int resolve_remote_symref(struct ref *ref, struct ref *list);
+int ref_newer(const unsigned char *new_sha1, const unsigned char *old_sha1);
 
 /*
  * Removes and frees any duplicate refs in the map.