SDEFER
sigtable[sig].s_flag &= ~SDEFER;
if (sigtable[sig].s_flag & SDEFER)
sigtable[sig].s_flag |= SDEFER;
sigtable[sig].s_flag |= SDEFER;
sigtable[sig].s_flag &= ~SDEFER;
if (sigtable[sig].s_flag & SDEFER)