Provide __module__ attributes for functions defined in C and Python.

__module__ is the string name of the module the function was defined
in, just like __module__ of classes.  In some cases, particularly for
C functions, the __module__ may be None.

Change PyCFunction_New() from a function to a macro, but keep an
unused copy of the function around so that we don't change the binary
API.

Change pickle's save_global() to use whichmodule() if __module__ is
None, but add the __module__ logic to whichmodule() since it might be
used outside of pickle.

Lib/test/test_funcattrs.py

@@ -9,6 +9,10 @@ def b():
     'my docstring'
     pass
 
+# __module__ is a special attribute
+verify(b.__module__ == __name__)
+verify(verify.__module__ == "test.test_support")
+
 # setting attributes on functions
 try:
     b.publish