[PATCH] Sema: Warn on sizeof on binary ops on decayed arrays.

[Benjamin Kramer]

  > Have you tried this on any other codebases to see if it digs up any other bugs?

  There were two instances in NetBSD, both had been fixed recently. Lacking resources to run it on more large corpuses.

  I'd expect this warning to trigger rarely, but if it does, it's always a bug.

http://llvm-reviews.chandlerc.com/D571