Before this PR, the linenumber infomaition is output if trailing-space
or tab code was found, but the output occurence is only per a file.
This PR separates the output timing of file name and line number.
As a result, users will find where they need to fix more easily.
Lint checks should not test these, they are historical documents,
and we don't want to encourage silly changes to them to satisfy
a checker.
Hopefully makes travis pass again on master.
Tree-SHA512: 37e6716c4fd5e8a4e579f9b84042e6b0ac224836b6c851cd1ca3f7d46611ffd3003bed0ae08dd0457f69d6eaa485a0d21c631e7ef16b14bdb0f2f78ea700332d
This adds a new CHECK_DOC check that looks for newly introduced trailing
whitespace. Existing trailing whitespace (of which there is plenty!)
will not trigger an error.
This is written in a generic way so that new lint-*.sh scripts can be
added to contrib/devtools/, as I'd like to contribute additional lint
checks in the future.
