IR: Represent -ggnu-pubnames with a flag on the DICompileUnit.

This allows the flag to be persisted through to LTO.

Differential Revision: https://reviews.llvm.org/D37655

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313078 91177308-0d34-0410-b5e6-96231b3b80d8
20 files changed