[PATCH] New warning for methods not marked 'override'

[Guillaume Papin]

  I haven't look to much into the details but are you aware of the cpp11-migrate tool that provides a similar functionality?
  I'm not saying that the diagnostic is not useful but maybe you can take a look at the implementation.
  For example at a quick glance it seems to me that if a method has an inline body the fix-hint will be misplaced.
  The check for macros such as LLVM_OVERRIDE may eventually be desired too.

  http://llvm-reviews.chandlerc.com/diffusion/L/browse/clang-tools-extra/trunk/cpp11-migrate/AddOverride/AddOverrideActions.cpp;187678$56

http://llvm-reviews.chandlerc.com/D1275