Enable seccomp on MIPS since libseccomp version 2.2.0 when MIPS support
was first added.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Acked-by: Eduardo Otubo <eduardo.otubo@profitbricks.com>