test, seccomp, Makefile: Switch to valgrind runs for passt functional tests

Pass to seccomp.sh a list of additional syscalls valgrind needs as
EXTRA_SYSCALLS in a new 'valgrind' make target, and add corresponding
support in seccomp.sh itself.

In test setup functions, start passt with valgrind, but not for
performance tests.

Add tests checking that valgrind exits without errors after all the
other tests in the group are done.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

seccomp.sh

@@ -234,6 +234,7 @@ printf '%s\n' "${HEADER}" > "${OUT}"
 __profiles="$(sed -n 's/[\t ]*\*[\t ]*#syscalls:\([^ ]*\).*/\1/p' *.[ch] | sort -u)"
 for __p in ${__profiles}; do
 	__calls="$(sed -n 's/[\t ]*\*[\t ]*#syscalls\(:'"${__p}"'\|\)[\t ]\{1,\}\(.*\)/\2/p' *.[ch])"
+	__calls="${__calls} ${EXTRA_SYSCALLS:-}"
 	__calls="$(filter ${__calls})"
 	echo "seccomp profile ${__p} allows: ${__calls}" | tr '\n' ' ' | fmt -t