use weak aliases rather than function pointers to simplify some code

[musl] / src / thread / sem_trywait.c

#include <semaphore.h>
#include "pthread_impl.h"

int sem_trywait(sem_t *sem)
{
        int val = sem->__val[0];
        if (val>0) {
                int new = val-1-(val==1 && sem->__val[1]);
                if (a_cas(sem->__val, val, new)==val) return 0;
        }
        errno = EAGAIN;
        return -1;
}