Issue #29263: LOAD_METHOD support for C methods

Calling builtin method is at most 10% faster.
diff --git a/Tools/gdb/libpython.py b/Tools/gdb/libpython.py
index cca9741..4f45256 100755
--- a/Tools/gdb/libpython.py
+++ b/Tools/gdb/libpython.py
@@ -1540,10 +1540,7 @@
 
         if caller in ('_PyCFunction_FastCallDict',
                       '_PyCFunction_FastCallKeywords'):
-            if caller == '_PyCFunction_FastCallKeywords':
-                arg_name = 'func_obj'
-            else:
-                arg_name = 'func'
+            arg_name = 'func'
             # Within that frame:
             #   "func" is the local containing the PyObject* of the
             # PyCFunctionObject instance