basic: Use _Static_assert() in missing_audit.h instead of assert_cc()

basic: Use _Static_assert() in missing_audit.h instead of assert_cc()

We want to make the header standalone so it includes all the stuff it
needs. However, including macro.h for assert_cc() doesn't work because
of generate-audit_type-list.sh which would have to become more complex
to handle the extra include directories.

Instead, let's just use _Static_assert() directly which is a builtin and
doesn't need any extra includes.