fix it so it's extensible and we'll avoid errors in future.

fix it so it's extensible and we'll avoid errors in future.

Often people will copy, paste and modify the "if" block, so let's do
it right from beginning.  What was wrong was the "" (empty string) as
initial SUBDIR.

git-svn-id: svn+ssh://svn.enlightenment.org/var/svn/e/trunk/evas@59213 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33