[CodeView] Implement function-type indices

We still need to do something about member functions and calling
conventions.

Differential Revision: http://reviews.llvm.org/D20900

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271541 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed