retain/release checker:

- Refactor a bunch of logic in the retain/release checker, making it more
  condense and easier to read.
- Add support for "Create" methods in the DiskArbitration framework

retain/release tests:
- Rename CFDate.m to retain-release.m, and move test from CFString.c to
  retain-release.m
- Add DiskArbitration framework tests cases.
- Add/refine and few more retain/release GC test cases.

llvm-svn: 62106