Allow calling of convenience functions with python

As mentioned in PR13326, currently when you try to call a
convenience function with python, you get this error:

(gdb) py print(gdb.convenience_variable("_isvoid")(3))
Traceback (most recent call last):
  File "<string>", line 1, in <module>
RuntimeError: Value is not callable (not TYPE_CODE_FUNC or TYPE_CODE_METHOD).
Error while executing Python code.

So this extends valpy_call to handle TYPE_CODE_INTERNAL_FUNCTION as
well, making this possible:

(gdb) py print(gdb.convenience_variable("_isvoid")(3))
0

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=13326
Approved-By: Tom Tromey <tom@tromey.com>

0 files changed, 0 insertions, 0 deletions