linux(4): Add support for __WALL wait option bit.

As FreeBSD does not have WALL option bit analogue explicitly set all
possible option bits to emulate Linux WALL wait option bit.

Reviewed by: emaste
Differential revision: https://reviews.freebsd.org/D31555
MFC after: 2 weeks

(cherry picked from commit c7ef7c3facaf663c3da2d91916bcb2f162fc300e)