Move -verify-pch to use VerifyJobAction

Use the verify hook rather than the compile hook to represent the
-verify-pch action, and move the exising --verify-debug-info action
into its own subclass of VerifyJobAction.  Incidentally change the name
printed by -ccc-print-phases for --verify-debug-info.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@200938 91177308-0d34-0410-b5e6-96231b3b80d8