Merge branch 'mt/dir-iterator-updates'

Adjust the dir-iterator API and apply it to the local clone
optimization codepath.

* mt/dir-iterator-updates:
clone: replace strcmp by fspathcmp
clone: use dir-iterator to avoid explicit dir traversal
clone: extract function from copy_or_link_directory
clone: copy hidden paths at local clone
dir-iterator: add flags parameter to dir_iterator_begin
dir-iterator: refactor state machine model
dir-iterator: use warning_errno when possible
dir-iterator: add tests for dir-iterator API
clone: better handle symlinked files at .git/objects/
clone: test for our behavior on odd objects/* content

diff --cc Makefile
Simple merge

diff --cc builtin/clone.c
Simple merge

diff --cc t/helper/test-tool.c
Simple merge

diff --cc t/helper/test-tool.h
Simple merge