[analyzer] RetainCount: Suppress retain detection heuristic on some CM methods.

If it ends with "Retain" like CFRetain and returns a CFTypeRef like CFRetain,
then it is not necessarily a CFRetain. But it is indeed true that these two
return something retained.

Differential Revision: https://reviews.llvm.org/D55907

rdar://problem/39390714

llvm-svn: 349862