tools: Go env vars should be derived from `go env`
tools: Go env vars should be derived from `go env`

* remove the hard restriction on go1.8 during `make tools`
* alpha sort `make debug` env vars

joyent/containerbuddy,joyent/containerbuddy,joyent/containerpilot,tgross/containerbuddy,tgross/containerbuddy,joyent/containerpilot,joyent/containerpilot