* E101: indentation contains mixed spaces and tabs
* E111: indentation is not a multiple of four
* E128: continuation line under-indented for visual indent
* E302: expected 2 blank lines, found 1
* W191: indentation contains tabs
This is only the driver side of the work; the frontend doesn't understand
this new -output-filelist option yet. Next commit.
More https://bugs.swift.org/browse/SR-280.