add context parameter to xmlrpclib.ServerProxy (#22960)

Patch by Alex Gaynor.

--HG--
branch : 3.4
merge 3.4 (#22960)
context is keyword-only

--HG--
branch : 3.4
merge 3.4
backout 9fcf4008b626 (#9179) for further consideration

--HG--
branch : 3.4
merge 3.4 (#9179)
Issue #22902: The "ip" command is now used on Linux to determine MAC address
in uuid.getnode().  Pach by Bruno Cauet.