resolve_gitlink_ref_recursive(): change to work with struct ref_cache

diff --git a/RelNotes b/RelNotes
index b9a53c3416991b66e1d35c2bbf663b48340b0041..766bbaf8f5a90759645200e1fc61e11d9836de49 120000 (symlink)
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes-1.6.0.txt
\ No newline at end of file
+Documentation/RelNotes/1.7.9.txt
\ No newline at end of file