Go 1.11 tools use $GOFLAGS automatically

[RJPercival]

Our Travis config uses an environment variable called $GOFLAGS to store the flags to pass to some Go commands it uses, e.g.

trillian/.travis.yml

Line 66 in 39f3d28

- go get ${GOFLAGS} -d -t ./...

Go 1.11 will read the $GOFLAGS variable itself so we won't need to use it as part of any commands. This will, however, possibly result in other go commands we use getting these flags where previously they didn't.

[daviddrysdale]

(Nothing to do until we move our Travis builds to use Go 1.11)

[daviddrysdale]

Also: gometalinter fixed upstream for this.