encoding/gob: save a call to userType Avoid some pressure on the global mutex by lifting the call to userType out of the closure. TOTH to Matt Harden.
encoding/gob: save a call to userType
Avoid some pressure on the global mutex by lifting the call to userType
out of the closure.
TOTH to Matt Harden.

LGTM=crawshaw, ruiu
R=golang-codereviews, crawshaw, ruiu
CC=golang-codereviews
https://codereview.appspot.com/117520043

d0f/go-zh,d0f/go-zh,webfd/go-zh,d0f/go-zh,sanjosh/sanjos100-tipc,sanjosh/sanjos100-tipc,bryanxu/go-zh,webfd/go-zh,sanjosh/sanjos100-tipc,bryanxu/go-zh,bryanxu/go-zh,d0f/go-zh,sanjosh/sanjos100-tipc,bryanxu/go-zh,webfd/go-zh,d0f/go-zh,webfd/go-zh,webfd/go-zh,d0f/go-zh,d0f/go-zh,sanjosh/sanjos100-tipc,webfd/go-zh,webfd/go-zh,bryanxu/go-zh,d0f/go-zh,bryanxu/go-zh,bryanxu/go-zh,sanjosh/sanjos100-tipc,bryanxu/go-zh,sanjosh/sanjos100-tipc,sanjosh/sanjos100-tipc,webfd/go-zh