the priority of the thread, specified by tid, within
the current process to the priority specified by newprio.
(For POSIX threads, see pthread_setschedparam(3THR).)
int thr_setprio(thread_t tid, int newprio)
By default, threads are scheduled based on fixed priorities that range
from zero, the least significant, to 127 the most significant.
int newprio = 20;
/* suspended thread creation */
ret = thr_create(NULL, NULL, func, arg, THR_SUSPENDED, &tid);
/* set the new priority of suspended child thread */
ret = thr_setprio(tid, newprio);
/* suspended child thread starts executing with new priority */
ret = thr_continue(tid);