test.pl: Don't assume existing watchdog uses alarm()

The fallback method of setting a watchdog timer is to use alarm(). Prior to this commit, the code presumed that if it wasn't one of the other possibilities, it must be this one. This is a valid assumption currently, but future commits will change that. Prepare for them with this commit.

Author: khwilliamson

t/test.pl

@@ -1838,6 +1838,7 @@ sub warning_like {
 { # Closure
  my $watchdog_process;
  my $watchdog_thread;
+ my $watchdog_alarm;
 
 sub watchdog ($;$)
 {
@@ -1854,8 +1855,9 @@ ($;$)
  kill('KILL', $watchdog_process);
  undef $watchdog_process;
  }
- else {
+ elsif ($watchdog_alarm) {
  alarm(0);
+ undef $watchdog_alarm;
  }
 
  return;
@@ -2060,6 +2062,7 @@ ($;$)
  my $sig = ($is_vms) ? 'TERM' : 'KILL';
  kill($sig, $pid_to_kill);
  };
+ $watchdog_alarm = 1;
  }
 }
 } # End closure