[Debugify] Do not report line 0 locations as errors

The checking logic should not treat artificial locations as being
somehow problematic. Producing these locations can be the desired
behavior of some passes.

See llvm.org/PR37961.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@335897 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed