xdiff/xprepare: improve O(n*m) performance in xdl_cleanup_records()

diff --git a/RelNotes b/RelNotes
index a9713ed41272daec5145d6b11091ea84d6469c67..6372427426d80b01b03437fd1a55fd412fb8f75d 120000 (symlink)
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes-1.7.0.6.txt
\ No newline at end of file
+Documentation/RelNotes/1.7.7.txt
\ No newline at end of file