Leave constructor initializer lists on one line in styles with no column limit.

Summary:
Allow tryFitMultipleLinesInOne join unwrapped lines when
ContinuationIndenter::mustBreak doesn't agree. But don't merge any lines, that
are separate in the input.

Reviewers: djasper

Reviewed By: djasper

CC: cfe-commits, klimek

Differential Revision: http://llvm-reviews.chandlerc.com/D2321