Add a preflight check for supported architecture

setup/preflight.sh

@@ -46,3 +46,17 @@ if [ -e ~/.wgetrc ]; then
 	echo "Mail-in-a-Box expects no overrides to wget defaults, ~/.wgetrc exists"
 	exit
 fi
+
+# Check that we are running on x86_64, any other architecture is unsupported and
+# will fail later in the setup when we try to install the custom build lucene packages.
+#
+# Set ARM=1 to ignore this check if you have built the packages yourself. If you do this
+# you are on your own!
+ARCHITECTURE=$(uname -m)
+if [ "$ARCHITECTURE" != "x86_64" ]; then
+if [ -z "$ARM" ]; then
+	echo "Mail-in-a-Box only supports x86_64 and will not work on any architecture like ARM."
+	echo "Your architecture is $ARCHITECTURE"
+	exit
+fi
+fi