[clang] Add PPCallbacks list to preprocessor when building a preacompiled preamble.

Summary:
Revision D38639 needs this commit in order to properly make open
definition calls on include statements work.

Patch by William Enright.

Reviewers: malaperle, krasimir, bkramer, ilya-biryukov

Reviewed By: malaperle, ilya-biryukov

Subscribers: cfe-commits, arphaman, ilya-biryukov

Differential Revision: https://reviews.llvm.org/D39375

llvm-svn: 320804