Rewrite llvm-lto's codegen() using ThinCodeGenerator::run(). NFC-ish.

Differential Revision: https://reviews.llvm.org/D33360

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303437 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed