[libcxx] Replace func_name with __name__ for compatibility with Python 3

Authored by broadwaylamb on Dec 6 2019, 11:17 AM.


[libcxx] Replace func_name with name for compatibility with Python 3

The name attribute is the correct way to get a function name in
Python 3. This also works with Python 2.

Reviewers: jroelofs, EricWF

Subscribers: christof, ldionne, libcxx-commits

Tags: #libc

Differential Revision: https://reviews.llvm.org/D71136