Revert "COFF: migrate def parser from LLD to LLVM"

This reverts commits r303490, r303491, r303493, and r303494.

This caused http://crbug.com/728726. Essentially, exporting stdcall
functions doesn't appear to work after this change. Reduced test case
soon.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304561 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed