ac97_str_equal
if (ac97_str_equal(class, si->class) &&
ac97_str_equal(device, si->device) &&
ac97_str_equal(qualifier, si->qualifier))
int ac97_str_equal(const char *, const char *);
ac97_str_equal(si->class, si2->class)) {
ac97_str_equal(si->class, si2->class) &&
ac97_str_equal(si->device, si2->device)) {