[codeview] Don't attempt a cross-section label diff

This only comes up when we're trying to find the next .cv_loc label.

Fixes PR26467

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@259733 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed