Log Message:
Add patch from Yuval Langer

Comment from the cherry-picked commit:
Defining thread priority for SCHED_OTHER is implementation defined.
Some platforms like NetBSD cannot reassign it as they are dynamic.

<http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_getschedparam.html>

Credit goes to kamil@netbsd.org and riastradh@netbsd.org for finding this
solution.

This should address PR pkg/50780 by Travis Paul