Tag the kvm-build with go version, avoid registry

Apparently make hates target names with colon in them, so avoid that.
Seems like we are not using $(REGISTRY), so avoid trying to pull it.

Makefile

@@ -34,7 +34,7 @@ HYPERKIT_BUILD_IMAGE 	?= karalabe/xgo-1.12.x
 # NOTE: "latest" as of 2019-07-12. kube-cross images aren't updated as often as Kubernetes
 BUILD_IMAGE 	?= k8s.gcr.io/kube-cross:v1.12.7-1
 ISO_BUILD_IMAGE ?= $(REGISTRY)/buildroot-image
-KVM_BUILD_IMAGE ?= $(REGISTRY)/kvm-build-image
+KVM_BUILD_IMAGE ?= $(REGISTRY)/kvm-build-image:$(GO_VERSION)
 
 ISO_BUCKET ?= minikube/iso
 
@@ -441,8 +441,7 @@ release-minikube: out/minikube checksum
 
 out/docker-machine-driver-kvm2: pkg/minikube/translate/translations.go
 ifeq ($(MINIKUBE_BUILD_IN_DOCKER),y)
-	docker inspect -f '{{.Id}} {{.RepoTags}}' $(KVM_BUILD_IMAGE) || \
-	docker pull $(KVM_BUILD_IMAGE) || $(MAKE) $(KVM_BUILD_IMAGE)
+	docker inspect -f '{{.Id}} {{.RepoTags}}' $(KVM_BUILD_IMAGE) || $(MAKE) kvm-image
 	$(call DOCKER,$(KVM_BUILD_IMAGE),/usr/bin/make $@ COMMIT=$(COMMIT))
 	# make extra sure that we are linking with the older version of libvirt (1.3.1)
 	test "`strings $@ | grep '^LIBVIRT_[0-9]' | sort | tail -n 1`" = "LIBVIRT_1.2.9"
@@ -473,15 +472,14 @@ out/docker-machine-driver-kvm2-$(RPM_VERSION).rpm: out/docker-machine-driver-kvm
 		out/docker-machine-driver-kvm2-$(RPM_VERSION)/docker-machine-driver-kvm2.spec
 	rm -rf out/docker-machine-driver-kvm2-$(RPM_VERSION)
 
-kvm-image: $(KVM_BUILD_IMAGE) # convenient alias to build the docker container
-$(KVM_BUILD_IMAGE): installers/linux/kvm/Dockerfile
-	docker build --build-arg "GO_VERSION=$(GO_VERSION)" -t $@ -f $< $(dir $<)
+.PHONY: kvm-image # convenient alias to build the docker container
+kvm-image: installers/linux/kvm/Dockerfile
+	docker build --build-arg "GO_VERSION=$(GO_VERSION)" -t $(KVM_BUILD_IMAGE) -f $< $(dir $<)
 	@echo ""
 	@echo "$(@) successfully built"
 
 kvm_in_docker:
-	docker inspect -f '{{.Id}} {{.RepoTags}}' $(KVM_BUILD_IMAGE) || \
-	docker pull $(KVM_BUILD_IMAGE) || $(MAKE) $(KVM_BUILD_IMAGE)
+	docker inspect -f '{{.Id}} {{.RepoTags}}' $(KVM_BUILD_IMAGE) || $(MAKE) kvm-image
 	rm -f out/docker-machine-driver-kvm2
 	$(call DOCKER,$(KVM_BUILD_IMAGE),/usr/bin/make out/docker-machine-driver-kvm2 COMMIT=$(COMMIT))