GlobalDCE: Teach isEmptyFunction() to ignore debug intrinsics.

This fixes PR39669.
https://bugs.llvm.org/show_bug.cgi?id=39669

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347065 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed