Fix a 3.6 CALL_FUNCTION_EX_KW problem..

and remove 3.6 customization from pysource.

test/simple_source/bug36/01_call_function.py

@@ -2,4 +2,9 @@
 # See https://github.com/rocky/python-uncompyle6/issues/58
 # CALL_FUNCTION_EX takes 2 to 3 arguments on the stack: the function, the tuple of positional arguments,
 # and optionally the dict of keyword arguments if bit 0 of oparg is 1.
-a(*[])
+from foo import f, dialect, args, kwds, reader
+
+f(*[])
+
+# From Python 3.6 csv.py
+x = reader(f, dialect, *args, **kwds)