test: Match gccgo error messages.
test: Match gccgo error messages.

Another case where gccgo and gc report similar but not
identical errors for a recursive interface.

bug251.go:11: error: invalid recursive interface

R=rsc
CC=golang-dev
http://codereview.appspot.com/2094041

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