WIP: minor build script fix

Author: marc-casavant

src/tests/multi-server/scripts/build_image.sh

@@ -1,4 +1,10 @@
 #!/bin/bash
+for arg in "$@"; do
+  case $arg in
+    BUILD_PLATFORM=*) BUILD_PLATFORM="${arg#*=}" ;;
+  esac
+done
+
 PLATFORM_ARG=""
 
 # This allows us to build an image on Apple Silicon where the base image was built on an linux/amd64 platform.