devel/gdb: Update to 11.1.

[jhb]

Summary

This also pulls in some updates to the libcxx-gdbpy to add a
pretty printer for std::unordered_map<>.

[jhb]

I have some other changes to libcxx-gdbpy I need to push to GitHub and update the hash in here again to add pretty printers for std::deque<> and std::stack<>.

[jhb]

• Update to newer libcxx-gdbpy.

[pizzamig]

Looks good to me.
In my tests, everything seems fine.
ready to land!