[clang-format] Add a few more Core Graphics identifiers to ObjC heuristic

Summary:
We received reports of the Objective-C style guesser getting a false
negative on header files like:

CGSize SizeOfThing(MyThing thing);

This adds more Core Graphics identifiers to the Objective-C style
guesser.

Test Plan: New tests added. Ran tests with:
  % make -j12 FormatTests && ./tools/clang/unittests/Format/FormatTests

Reviewers: jolesiak, djasper

Reviewed By: jolesiak, djasper

Subscribers: krasimir, klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D44632

llvm-svn: 328175