If we receive a signal from the command we executed, do not forward

it back to the command.  This fixes a problem with BSD-derived
versions of the reboot command which send SIGTERM to all other
processes, including the sudo process.  Sudo would then deliver
SIGTERM to reboot which would die before calling the reboot() system
call, effectively leaving the system in single user mode.

src/sudo.h

@@ -165,6 +165,7 @@ struct command_status {
 #define CMD_ERRNO 1
 #define CMD_WSTATUS 2
 #define CMD_SIGNO 3
+#define CMD_PID 4
     int type;
     int val;
 };