Fix crash: do not list job if in 60 sec grace period (re: 3385868)

The crash in job_list() or job_unpost() could still occur after the
previous patch if a signal was being handled after $TMOUT was
exceeded and the 60-second grace period was entered.

It *should* work to add a general check for !sh_isstate(SH_GRACE).
We know that the SH_GRACE state is set immediately after printing
the 60 second grace period warning message:
https://github.com/ksh93/ksh/blob/9de65210/src/cmd/ksh93/sh/io.c#L1869-L1870
(and that the crashes occur upon re-evaluating the $PS1 prompt
after setting the SH_GRACE state). We know that the SH_GRACE state
is not turned off again until either the user enters a line:
https://github.com/ksh93/ksh/blob/9de65210/src/cmd/ksh93/sh/main.c#L474
or the shell times out after the grace period:
https://github.com/ksh93/ksh/blob/9de65210/src/cmd/ksh93/sh/io.c#L1861
The SH_GRACE state flag is not used or changed in any other context
(verified with grep -rn SH_GRACE src/cmd/ksh93). So, logically,
this should suffice to make sure the crash stays gone.

src/cmd/ksh93/sh/jobs.c: job_reap():
- Do not list jobs when the SH_GRACE state (the 60 second timeout
  grace period after TMOUT was exceeded) is active.
- Keep the previous check for job control just to be sure, and
  because it makes sense.

Fixes: #103 (again)

NEWS

@@ -3,11 +3,14 @@ For full details, see the git log at: https://github.com/ksh93/ksh
 
 Any uppercase BUG_* names are modernish shell bug IDs.
 
-2020-08-06:
+2020-08-07:
 
-- Fixed a crash that occurred intermittently if 'set -b'/'set -o notify' is
+- Fixed a crash that occurred intermittently when entering the 60 second
+  timeout grace period after exceeding $TMOUT, if 'set -b'/'set -o notify' is
   active and $PS1 contains a command substitution running an external command.
 
+2020-08-06:
+
 - Added the '${.sh.pid}' variable as an alternative to Bash's '$BASHPID'.
   This variable is set to the current shell's PID, unlike '$$' (which is
   set to the parent shell's PID). In virtual subshells '${.sh.pid}' is not

src/cmd/ksh93/include/version.h

@@ -17,4 +17,4 @@
 *                  David Korn <[email protected]>                   *
 *                                                                      *
 ***********************************************************************/
-#define SH_RELEASE	"93u+m 2020-08-06"
+#define SH_RELEASE	"93u+m 2020-08-07"

src/cmd/ksh93/sh/jobs.c

@@ -460,7 +460,7 @@ int job_reap(register int sig)
 		nochild = 1;
 	}
 	shp->gd->waitevent = waitevent;
-	if(job.jobcontrol && sh_isoption(SH_NOTIFY) && sh_isstate(SH_TTYWAIT))
+	if(job.jobcontrol && sh_isoption(SH_NOTIFY) && sh_isstate(SH_TTYWAIT) && !sh_isstate(SH_GRACE))
 	{
 		outfile = sfstderr;
 		job_list(pw,JOB_NFLAG|JOB_NLFLAG);