test-lib: introduce test_line_count to measure files

diff --git a/RelNotes b/RelNotes
index 8fbe7db0e2a61ae4952f611b02d5a61bbcaf2b77..50b2d422d80b2a0c8976c56422a2b851dbcd4a50 120000 (symlink)
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes-1.5.4.7.txt
\ No newline at end of file
+Documentation/RelNotes/1.7.3.1.txt
\ No newline at end of file