Merge branch 'jc/checkdiff'

* jc/checkdiff:
Fix t4017-diff-retval for white-space from wc
Update sample pre-commit hook to use "diff --check"
diff --check: detect leftover conflict markers
Teach "diff --check" about new blank lines at end
checkdiff: pass diff_options to the callback
check_and_emit_line(): rename and refactor
diff --check: explain why we do not care whether old side is binary

diff --cc builtin-apply.c
Simple merge

diff --cc diff.c
Simple merge