Summary:
This patch fixes an error happening in TestNumThreads.py when it encounters frame.GetFunctionName none for address only locations in stripped libc.
This error was showing up on arm-linux docker container running lldb buildbot.
Reviewers: labath
Reviewed By: labath
Subscribers: kristof.beyls, lldb-commits
Differential Revision: https://reviews.llvm.org/D79777