signalnext
if (numsig == 0 || signalnext(numsig) == -1)
if (numsig != 0 && signalnext(numsig) == -1)
for (sig = 0; (sig = signalnext(sig)) != 0; ) {
for (sig = 0; (sig = signalnext(sig)) != 0; ) {
int signalnext(int);