Merge branch 'tb/apply-with-crlf' into maint

Merge branch 'tb/apply-with-crlf' into maint

"git apply" that is used as a better "patch -p1" failed to apply a
taken from a file with CRLF line endings to a file with CRLF line
endings.  The root cause was because it misused convert_to_git()
that tried to do "safe-crlf" processing by looking at the index
entry at the same path, which is a nonsense---in that mode, "apply"
is not working on the data in (or derived from) the index at all.
This has been fixed.

* tb/apply-with-crlf:
  apply: file commited with CRLF should roundtrip diff and apply
  convert: add SAFE_CRLF_KEEP_CRLF