Fix platform to linux/amd64.

Change-Id: Ia6601b4cb63b0fc6f9137d0947a6681f1d9a803a
diff --git a/openjdk-runtime/build b/openjdk-runtime/build
index 629823b..5b94efc 100755
--- a/openjdk-runtime/build
+++ b/openjdk-runtime/build
@@ -9,6 +9,7 @@
 
 image=docker.benkard.de/mulk/openjdk-runtime:latest
 dependencies=(registry.access.redhat.com/ubi9/ubi-micro:latest registry.access.redhat.com/ubi9/ubi-minimal:latest)
+platform=linux/amd64
 use_kaniko=no
 
 ./prepare
@@ -16,6 +17,7 @@
 if [[ "${use_kaniko}" == yes ]]; then
     docker run \
         --mount type=bind,src="$PWD",target=/workspace \
+        --platform "${platform}" \
         gcr.io/kaniko-project/warmer:latest \
         --cache-dir=/workspace/cache \
         --image=registry.access.redhat.com/ubi9/ubi-micro:latest \
@@ -24,6 +26,7 @@
     docker run \
         --mount type=bind,src="$PWD",target=/workspace \
         --mount type=bind,src="$HOME/.docker",target=/root/.docker,ro=true \
+        --platform "${platform}" \
         gcr.io/kaniko-project/executor:latest \
         --dockerfile Dockerfile \
         --destination "${image}" \
@@ -33,8 +36,8 @@
         --reproducible=true
 else
     for x in "${dependencies[@]}"; do
-        docker pull "$x"
+        docker pull --platform "${platform}" "$x"
     done
-    docker build -t "${image}" .
+    docker build --platform "${platform}" -t "${image}" .
     docker push "${image}"
 fi