cocci: have "coccicheck{,-pending}" depend on "coccicheck-test"

cocci: have "coccicheck{,-pending}" depend on "coccicheck-test"

Have the newly introduced "coccicheck-test" target run implicitly when
"coccicheck" itself is run. As with e.g. the "check-chainlint"
target (see [1]) it makes sense to run this unconditionally before we
run other "spatch" rules as a basic sanity check. See

1. 803394459d4 (t/Makefile: add machinery to check correctness of
   chainlint.sed, 2018-07-11)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>