scripts: fix installing samples

It's been a while now that the working directory CT_WORK_DIR has
been changed from 'targets' to '.build'. Fix the install procedure
to properly tweak the installed samples.

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

 reporter_name="Harold Grovesteen"

 reporter_url="http://sourceware.org/ml/crossgcc/2009-11/msg00052.html"

 reporter_comment=""