save 90MB by removing foreign binaries -- multi-platform installations are unlikely on Windows;

--- a/Admin/makebundle	Wed May 02 20:43:57 2012 +0200
+++ b/Admin/makebundle	Wed May 02 20:57:59 2012 +0200
@@ -76,6 +76,15 @@
   rm -f "$ISABELLE_HOME/Isabelle"
   tar -C "$ISABELLE_HOME" -xv -f "$TAR"
 
+  (
+    cd "$ISABELLE_HOME"
+    for DIR in $(find contrib -name x86-linux -o -name x86_64-linux -o -name x86-darwin -o -name x86_64-darwin | sort)
+    do
+      echo "removing $DIR"
+      rm -rf "$DIR"
+    done
+  )
+
   mv "$ISABELLE_HOME/contrib"/polyml* "$ISABELLE_HOME/contrib/cygwin-1.7.9/usr/local/"
   (
     cd "$ISABELLE_HOME/contrib/cygwin-1.7.9"