[codeview] Stop emitting fully qualified subprogram display names

This effectively reverts r255744, and leaves the printing option tweaks.

We can add the name qualifiers easily in the backend.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@273008 91177308-0d34-0410-b5e6-96231b3b80d8