Posix: Add initial stub for atomic HRT The actual implementation is not atomic, as the value on the application layer would be limited.
Posix: Add initial stub for atomic HRT
The actual implementation is not atomic, as the value on the application layer would be limited.

acfloria/Firmware,krbeverx/Firmware,acfloria/Firmware,dagar/Firmware,mje-nz/PX4-Firmware,PX4/Firmware,dagar/Firmware,dagar/Firmware,krbeverx/Firmware,acfloria/Firmware,krbeverx/Firmware,acfloria/Firmware,dagar/Firmware,mje-nz/PX4-Firmware,krbeverx/Firmware,mje-nz/PX4-Firmware,krbeverx/Firmware,mje-nz/PX4-Firmware,acfloria/Firmware,PX4/Firmware,dagar/Firmware,krbeverx/Firmware,mje-nz/PX4-Firmware,PX4/Firmware,PX4/Firmware,acfloria/Firmware,PX4/Firmware,krbeverx/Firmware,PX4/Firmware,dagar/Firmware,PX4/Firmware,mje-nz/PX4-Firmware,acfloria/Firmware,mje-nz/PX4-Firmware,dagar/Firmware