Message 415780 - Python tracker

Currently, Tools/gdb/libpython.py uses PyFramePtr.iter_locals() which iterates on PyFrameObject.f_frame.localsplus.

There is a PyFramePtr.get_var_by_name() function which only checks for frame variables in PyFrameObject.f_frame.localsplus, or look up in globals and builtins. So it only supports some kinds of variables.