Complete r302215. TDF_SBDRY | TDF_SERESTART and TDF_SBDRY |
TDF_SEINTR flags values, unlike TDF_SBDRY, must be treated almost as
if TDF_SBDRY is not set for STOP signal delivery. The only difference
is that sig_suspend_threads() should abort the sleep instead of doing
immediate suspension.

Reported by: ngie
Sponsored by: The FreeBSD Foundation
MFC after: 12 days
Approved by: re (gjb)