Since these are just interpreted comments, there's 0 impact on actual code.
This removes all lines that match /* vim: set(.*)tw=80: */ with S&R -- there are
a few others scattered around which will be removed manually in a second part.
Includes removing an error code for a function that never fails, and removing an
error return when the function successfully did what it said it would.
Ref: BZ 1644477
