[CodeView] Emit an appropriate symbol kind for globals

[CodeView] Emit an appropriate symbol kind for globals

We emitted debug info for globals/functions as if they all had external
linkage.  Instead, emit local symbol records when appropriate.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274676 91177308-0d34-0410-b5e6-96231b3b80d8