spec: disallow general func, map comparisons
spec: disallow general func, map comparisons

R=golang-dev, gri, r, r
CC=golang-dev
http://codereview.appspot.com/5369090

tv42/old-go,dsriram/golang,dsriram/golang,gnanderson/go,apparentlymart/golang,apparentlymart/golang,gnanderson/go,gnanderson/go,tv42/old-go,pombredanne/go-deleteme,dsriram/golang,tv42/old-go,dsriram/golang,pombredanne/go-deleteme,gnanderson/go,gnanderson/go,tv42/old-go,pombredanne/go-deleteme,apparentlymart/golang,gnanderson/go,apparentlymart/golang,dsriram/golang,dsriram/golang,pombredanne/go-deleteme,tv42/old-go,apparentlymart/golang,apparentlymart/golang,tv42/old-go,pombredanne/go-deleteme,pombredanne/go-deleteme,pombredanne/go-deleteme,apparentlymart/golang,dsriram/golang,tv42/old-go,gnanderson/go