[CrossTU] Added CTU argument to diagnostic consumer create fn.

Summary:
The PListDiagnosticConsumer needs a new CTU parameter that is passed
through the create functions.

Reviewers: NoQ, Szelethus, xazax.hun, martong

Reviewed By: Szelethus

Subscribers: rnkovacs, dkrupp, Szelethus, gamesh411, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D64635

llvm-svn: 366782