cmd/gc: remove node printing in redeclare errors
cmd/gc: remove node printing in redeclare errors

I suspect this is some debugging which got through the submission process.

Fixes issue 4789.

R=golang-dev, rsc
CC=golang-dev
https://codereview.appspot.com/7310079
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go