seccomp: assume clone() arg order is known on all architectures

While adding the defines for arm, I realized that we have pretty much all
known architectures covered, so SECCOMP_RESTRICT_NAMESPACES_BROKEN is not
necessary anymore. clone(2) is adamant that the order of the first two
arguments is only reversed on s390/s390x. So let's simplify things and remove
the #if.

src/test/test-seccomp.c

@@ -160,8 +160,6 @@ static void test_restrict_namespace(void) {
         assert_se(streq(s, "cgroup ipc net mnt pid user uts"));
         assert_se(namespace_flag_from_string_many(s, &ul) == 0 && ul == NAMESPACE_FLAGS_ALL);
 
-#if SECCOMP_RESTRICT_NAMESPACES_BROKEN == 0
-
         if (!is_seccomp_available())
                 return;
         if (geteuid() != 0)
@@ -220,7 +218,6 @@ static void test_restrict_namespace(void) {
         }
 
         assert_se(wait_for_terminate_and_warn("nsseccomp", pid, true) == EXIT_SUCCESS);
-#endif
 }
 
 static void test_protect_sysctl(void) {