scripts/functions: properly catch failure in CT_Test* helpers

So we get caught by the trap-handler and
have a chance to run the debug-shell.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Johannes Stezenbach <js@sig21.net>

 reporter_name="YEM"

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

 reporter_comment="EXPERIMENTAL Super-H sh4 sample."