coccicheck: Allow to show the executed command line

On my system one of the tests failed with
"Fatal error: exception Failure("No OCaml compiler found! Install either ocamlopt or ocamlopt.opt")".

Investigating such issues is easier if the executed command line is
being shown.

Signed-off-by: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
CC: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Nicolas Palix <nicolas.palix@imag.fr>
Signed-off-by: Michal Marek <mmarek@suse.cz>