Refactor, do not touch disk if coming from PCH (slc6->slc7).

(cherry picked from commit 5ff964488bcc7bf27636936961caabf01db91000)
Do not extract comments from source for decls coming from the PCH (slc6->7).

(cherry picked from commit 3c289a291a5c040deacce8a253e551498a931553)