TSTP_FORK
whystopped == TSTP_FORK);
ASSERT((whystopped & (TSTP_REGULAR|TSTP_MUTATOR|TSTP_FORK)) != 0);
ASSERT((whystopped & ~(TSTP_REGULAR|TSTP_MUTATOR|TSTP_FORK)) == 0);
if (whystopped & TSTP_FORK) {
ulwp->ul_stop |= TSTP_FORK;
if (safe_suspend(ulwp, TSTP_FORK, &link_dropped) ||
ASSERT(ulwp->ul_stop & TSTP_FORK);
ulwp->ul_stop &= ~TSTP_FORK;