seccomp: fix SECCOMP_USER_NOTIF_FLAG_CONTINUE test

The ifndef for SECCOMP_USER_NOTIF_FLAG_CONTINUE was placed under the
ifndef for the SECCOMP_FILTER_FLAG_NEW_LISTENER feature. This will not
work on systems that do support SECCOMP_FILTER_FLAG_NEW_LISTENER but do not
support SECCOMP_USER_NOTIF_FLAG_CONTINUE. So move the latter ifndef out of
the former ifndef's scope.

2019-10-20 11:14:01 make run_tests -C seccomp
make: Entering directory '/usr/src/perf_selftests-x86_64-rhel-7.6-0eebfed2/tools/testing/selftests/seccomp'
gcc -Wl,-no-as-needed -Wall  seccomp_bpf.c -lpthread -o seccomp_bpf
seccomp_bpf.c: In function ‘user_notification_continue’:
seccomp_bpf.c:3562:15: error: ‘SECCOMP_USER_NOTIF_FLAG_CONTINUE’ undeclared (first use in this function)
  resp.flags = SECCOMP_USER_NOTIF_FLAG_CONTINUE;
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
seccomp_bpf.c:3562:15: note: each undeclared identifier is reported only once for each function it appears in
Makefile:12: recipe for target 'seccomp_bpf' failed
make: *** [seccomp_bpf] Error 1
make: Leaving directory '/usr/src/perf_selftests-x86_64-rhel-7.6-0eebfed2

/tools/testing/selftests/seccomp'

Reported-by: kernel test robot <rong.a.chen@intel.com>
Fixes: 0eebfed2

 ("seccomp: test SECCOMP_USER_NOTIF_FLAG_CONTINUE")
Cc: linux-kselftest@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Tycho Andersen <tycho@tycho.ws>
Link: https://lore.kernel.org/r/20191021091055.4644-1-christian.brauner@ubuntu.com
Signed-off-by: Kees Cook <keescook@chromium.org>