scripts: fix stripping in finalisation step

The heuristic to find shell script is deficient. Fix it.

Reported-by: Kyle Grieb <grieb.kyle@gmail.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
(transplanted from ade5d48d98f27ba75e28c2f559f1eec9e76e9c59)

 reporter_name="Harold Grovesteen"

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

 reporter_comment=""