checkdeps: encode input to os.walk as utf-8.

Also fix checkdeps_test.py after the move into chromium/src.

Bug: 962059
Change-Id: I86f041e5ce819e0fbf3fb1e4de29fdde6c8d4596
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1610222
Auto-Submit: John Budorick <[email protected]>
Reviewed-by: Thomas Anderson <[email protected]>
Commit-Queue: John Budorick <[email protected]>
Cr-Commit-Position: refs/heads/master@{#659173}
11 files changed