test.pl: Simpler method to cancel watchdog timers

The added END block can simply call watchdog(0), which already has the
knowledge to be able to cancel whichever watachdog method is used.

Spotted by Tony Cook

A comment is added as to why no cancellation is needed of a watchdog
implemented by alarm().

Even though a test file should clear every timer before exit, this makes
sure it happens.

Author: khwilliamson

t/test.pl

@@ -1952,8 +1952,7 @@ ($;$)
 
                 # Add END block to parent to terminate and clean up watchdog
                 # process
-                eval("END { local \$! = 0; local \$? = 0;
-                            wait() if kill('KILL', $watchdog); };");
+                eval("END { watchdog(0); };");
                 return;
             }
 
@@ -1969,8 +1968,7 @@ ($;$)
             if ($watchdog) {   # Parent process
                 # Add END block to parent to terminate and clean up watchdog
                 # process
-                eval "END { local \$! = 0; local \$? = 0;
-                            wait() if kill('KILL', $watchdog); };";
+                eval("END { watchdog(0); };");
                 return;
             }
 
@@ -2060,6 +2058,9 @@ ($;$)
             my $sig = $is_vms ? 'TERM' : 'KILL';
             kill($sig, $pid_to_kill);
         };
+
+        # No need to clear a watchdog implemented by alarm(); it goes away
+        # automatically when the process dies
     }
 }
 } # End closure