[RHEL8][CONTAINER] Runtime check when creating pThreads

It looks like :
  - when running on a Fedora-host
  - with generic kernel
  - in a container
  - even in privileged mode

That is not enough and priority/schedule settings is not allowed.

So at runtime, we check and in case, we don't set up priorities.

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>