MFH: r452622

Mark BROKEN: fails to build with go 1.9

gmake[1]: Entering directory '/wrkdirs/usr/ports/databases/cockroach/work/cockroach-v1.0.4/src/github.com/cockroachdb/cockroach'
build/common.mk:110: *** "go1\.8.* required (see CONTRIBUTING.md): go version go1.9.1 freebsd/amd64". Stop.

Reported by: pkg-fallout