seccomp: no need to check arch in syscall whitelist

v2 update:
- set libseccomp 2.1.0 as requirement on configure script.

Since libseccomp 2.0 there's no need to check the architecture type
anymore.

Signed-off-by: Eduardo Otubo <otubo@linux.vnet.ibm.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1374518017-10424-2-git-send-email-otubo@linux.vnet.ibm.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
