Linux shared memory of tasks for exec driver /dev/shm

we actually used the raw_exec driver and ran these procs without isolation to access the host shared memory as is (/dev/shm).

this post/answer was immensely helpful. We used nomad 1.10.5 that addressed the issue.

we also need a poststop task to reap all the child processes stopped, as the raw_exec leaves some child procs behind.