Rebase fix for PR #646

I needed this for my arm64 k8s cluster. I have zero Go experience but
enough experience with other things to fix the rebase (I think!). This
patch is working fine on my cluster.

deploy/Dockerfile_warmer

@@ -15,6 +15,7 @@
 # Builds the static Go image to execute in a Kubernetes job
 
 FROM golang:1.12
+ARG GOARCH=amd64
 WORKDIR /go/src/github.com/GoogleContainerTools/kaniko
 # Get GCR credential helper
 ADD https://github.com/GoogleCloudPlatform/docker-credential-gcr/releases/download/v1.5.0/docker-credential-gcr_linux_amd64-1.5.0.tar.gz /usr/local/bin/
@@ -25,7 +26,7 @@ RUN go get -u github.com/awslabs/amazon-ecr-credential-helper/ecr-login/cli/dock
 RUN make -C /go/src/github.com/awslabs/amazon-ecr-credential-helper linux-amd64
 
 COPY . .
-RUN make out/warmer
+RUN make GOARCH=${GOARCH} out/warmer
 
 FROM scratch
 COPY --from=0 /go/src/github.com/GoogleContainerTools/kaniko/out/warmer /kaniko/warmer