Linux.x64 fix for 'sbjclean' stub script.

xtrn/sbj/sbjclean

 #!/bin/sh
 os=`uname | tr "[A-Z]" "[a-z]"`
+if [ `arch` = x86_64 ]; then os=$os.x64; fi
 exename=`basename $0`
 dirname=`dirname $0`
 if [ -x $dirname\/gcc.$os.exe.release/$exename ]