go spec: minor clarification of scope rule for functions
go spec: minor clarification of scope rule for functions

R=rsc, iant, r, r2
CC=golang-dev
http://codereview.appspot.com/4256050

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang