Instead of dual-purposing a single flag, rename the driver option to
--verify-debug-info.
The frontend -verify option that enables diagnostic verification remains
unchanged except that it's now a pure CC1Option.
Both have been given proper help text.
llvm-svn: 199451
output on darwin so is hard coded there.
As a note this will need a little bit of refactoring in the class
hierarchy to separate it out for different verifiers based on input type.
Fixes rdar://8256258.
llvm-svn: 138343