[analyzer] Implement "Loop executed 0 times" diagnostic correctly.

Fixes <rdar://problem/13236549>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175863 91177308-0d34-0410-b5e6-96231b3b80d8
Teach -ast-print how to print trailing-return-types.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175864 91177308-0d34-0410-b5e6-96231b3b80d8