More storage provisioner fixes.

I'm not sure of a better way to ensure /tmp exists in a from scratch container,
but glog appears to just explode without it.

Makefile

@@ -301,7 +301,7 @@ $(ISO_BUILD_IMAGE): deploy/iso/minikube-iso/Dockerfile
 	@echo "$(@) successfully built"
 
 out/storage-provisioner: $(shell $(STORAGE_PROVISIONER_FILES))
-	go build GOOS=linux -o $(BUILD_DIR)/storage-provisioner -ldflags=$(LOCALKUBE_LDFLAGS) cmd/storage-provisioner/main.go
+	GOOS=linux go build -o $(BUILD_DIR)/storage-provisioner -ldflags=$(LOCALKUBE_LDFLAGS) cmd/storage-provisioner/main.go
 
 .PHONY: storage-provisioner-image
 storage-provisioner-image: out/storage-provisioner

cmd/storage-provisioner/main.go

@@ -18,11 +18,19 @@ package main
 
 import (
 	"flag"
+	"fmt"
+	"os"
+
 	"github.com/golang/glog"
 	"k8s.io/minikube/pkg/localkube"
 )
 
 func main() {
+	// Glog requires that /tmp exists.
+	if err := os.MkdirAll("/tmp", 0755); err != nil {
+		fmt.Printf("Error creating tmpdir: %s\n", err)
+		os.Exit(1)
+	}
 	flag.Parse()
 
 	if err := localkube.StartStorageProvisioner(); err != nil {