test: match gccgo error messages for bug274.go.
test: match gccgo error messages for bug274.go.

bug274.go:23:3: error: missing statement after label
bug274.go:25:3: error: missing statement after label
bug274.go:28:3: error: label ‘L2’ defined and not used

R=rsc
CC=golang-dev
http://codereview.appspot.com/4273114

tav/go,tav/go,tav/go,tav/go,tav/go,tav/go,tav/go