Fix arc handling of "\n" files on Windows in SVN
Summary:
On Windows, a diff may have "\n" newlines (from the file itself) but "\r\n" blocks (from svn).
NOTE: indents are funky since I edited this with Notepad++, I'll fix before landing.
Test Plan: Diffed an edit to a "\n" newline file on Windows in SVN.
Reviewers: btrahan, vrana
Reviewed By: vrana
CC: aran
Differential Revision: https://secure.phabricator.com/D2998