[clang-format] Align trailing comments if ColumnLimit is 0
ColumnLimit = 0 means no limit, so comment should always be aligned if requested. This was broken with
and is included in 5.0.0-rc2. This commit fixes it and adds a unittest for this property.
Should go into clang-5.0 IMHO.
Contributed by @pboettch!
Reviewers: djasper, krasimir
Reviewed By: djasper, krasimir
Subscribers: hans, klimek
Differential Revision: https://reviews.llvm.org/D36967