Pass a (ref_cache *) to the resolve_gitlink_*() helper functions

diff --git a/RelNotes b/RelNotes
index 6372427426d80b01b03437fd1a55fd412fb8f75d..766bbaf8f5a90759645200e1fc61e11d9836de49 120000 (symlink)
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes/1.7.7.txt
\ No newline at end of file
+Documentation/RelNotes/1.7.9.txt
\ No newline at end of file