Silencing a rather spurious warning from MSVC 11 about not all control paths returning a value (hint: they do).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189605 91177308-0d34-0410-b5e6-96231b3b80d8
Silencing the warning from r189605 in a more conformant manner.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189606 91177308-0d34-0410-b5e6-96231b3b80d8
Debug Info: this reverts commit r189600.

We had further discussions on how to retain types, whether to do it in front end
or in DIBuilder. And we agree to do it in DIBuilder so front ends
generating unique identifier do not need to worry about retaining them.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189609 91177308-0d34-0410-b5e6-96231b3b80d8