Allow command in target-list

The patch below makes configure --target-list accept a comma separated list of targets, as well as a space separated list. This is easier to protect from the shell, and more consistent with other configure scripts.

Space separated lists are still accepted as before.

Paul

Index: configure
===================================================================
@@ -215,6 +215,8 @@
     if [ "$linux" = "yes" ] ; then
         target_list="i386-user arm-user armeb-user sparc-user ppc-user 

$target_list"
fi
+else
+ target_list=$(echo "$target_list" | sed -e 's/,/ /g')
fi

if test -z "$cross_prefix" ; then