The scheme48.image entry point procedure prints a welcome message that
includes "built by Fred" where Fred is the username of the user that
built Scheme48.  Make this be the output of `hostname -s`
Index: scheme48/build/build-usual-image
===================================================================
--- scheme48.orig/build/build-usual-image	2013-03-14 10:12:04.000000000 +0100
+++ scheme48/build/build-usual-image	2013-03-14 10:12:04.000000000 +0100
@@ -14,7 +14,7 @@
 image=$4
 vm=$5
 initial=$6
-USER=${USER-`logname 2>/dev/null || echo '*GOK*'`}
+USER=$(hostname -s)
 
 $vm -i $initial -a batch <<EOF
 ,load $srcdir/scheme/env/init-defpackage.scm