getopt: fix null pointer arithmetic ub

[musl] / src / thread / pthread_attr_setguardsize.c

#include "pthread_impl.h"

int pthread_attr_setguardsize(pthread_attr_t *a, size_t size)
{
        if (size > SIZE_MAX/8) return EINVAL;
        a->_a_guardsize = size;
        return 0;
}