test-lib: introduce test_line_count to measure files

diff --git a/RelNotes b/RelNotes
index 1cb2571eaae44b1e01fa4713c6c4b147eed9ac4a..50b2d422d80b2a0c8976c56422a2b851dbcd4a50 120000 (symlink)
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes-1.6.5.2.txt
\ No newline at end of file
+Documentation/RelNotes/1.7.3.1.txt
\ No newline at end of file