[PATCH] Allow specifying a custom PathDiagnosticConsumer for use with the static analyzer.

[Jordan Rose]

  > The problem is, that we not only need the checker name as a part of the message (which is a nice side-effect), but as a separate piece of data, and I wouldn't like to parse it out of the message.

  Then again, why aren't we improving the existing data formats and the tools meant to consume them? (cf. the now-inappropriately-named CmpRuns.py)

  I'm consciously giving you a hard time because I've watched the plist output leave the HTML output in the dust. scan-build on its own is //much// worse at reporting errors, to the point where we don't even show paths that cross files because no one has put in the time to make that work in a nice way. I don't want to see clang-tidy get all these nice features that don't translate into the plists or Xcode, and I don't want clang-tidy to have to spend a ton of effort to get the //existing// features of the plists and Xcode. As much as possible, I want to have one code path.

http://llvm-reviews.chandlerc.com/D2556