scripts: fix default work-dir name

It's been a long time the default work-dir changed its name
from 'target' to '.build'.

Change the left-over.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

 reporter_name="YEM"

 reporter_url="http://ymorin.is-a-geek.org/"

 reporter_comment="EXPERIMENTAL Super-H sh4 sample."