Make 41 Go ports respect MAKE_ENV. This is expected to unbreak them.

Ports:
benchmarks/hey benchmarks/vegeta databases/influxdb devel/arduino-builder devel/arduinoOTA
devel/awless devel/git-codereview devel/git-town devel/gitlab-runner devel/grv
devel/hub devel/jfrog-cli editors/micro finance/fixc misc/exercism
net-mgmt/intel-snap net-mgmt/kapacitor net-mgmt/telegraf net/goreplay net/syncthing
net/syncthing-cli net/syncthing-discosrv net/syncthing-inotify print/cups-connector security/sops
security/vault sysutils/amazon-ssm-agent sysutils/circonus-agent sysutils/consul sysutils/consul_exporter
sysutils/envconsul sysutils/serf textproc/consul-template textproc/spiff www/gobuffalo
www/grafana2 www/grafana3 www/mattermost-server www/minio www/minio-client
www/uchiwa

Approved by: tcberner (mentor, implicit)
Approved by: portmgr (port compliance, infrastructure)