switched from using sed to perl in mirabelle tool

--- a/src/HOL/Mirabelle/lib/Tools/mirabelle	Sat Apr 14 23:52:17 2012 +0100
+++ b/src/HOL/Mirabelle/lib/Tools/mirabelle	Sat Apr 14 23:52:17 2012 +0100
@@ -11,7 +11,7 @@
   ACTIONS="$MIRABELLE_HOME/Actions/mirabelle_*.ML"
   for ACTION in $ACTIONS
   do
-    echo $ACTION | sed 's/.*mirabelle_\(.*\)\.ML/    \1/'
+    echo $ACTION | perl -w -p -e 's/.*mirabelle_(.*)\.ML/    $1/'
   done
 }