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>

 python

 import sys

 sys.path.insert(0, '@@PREFIX@@/share/gcc-@@VERSION@@/python')

 from libstdcxx.v6.printers import register_libstdcxx_printers

 register_libstdcxx_printers (None)

 end