Set a generic yet descriptive hostname

The default is to inherit the hostname from the build environment.

scripts/set-generic-hostname

@@ -0,0 +1,11 @@
+#!/bin/sh -eu
+# set-generic-hostname -- to a descriptive, reproducible string
+# Copyright (C) 2017  Olaf Meeuwissen
+#
+# License: GPL-3.0+
+
+. /etc/os-release
+echo $ID-$(cat /etc/${ID}_version) > /etc/hostname
+chmod 0644 /etc/hostname
+
+rm $0