Fix pcntl extension error for queue (#15393)

src/Illuminate/Queue/Console/ListenCommand.php

@@ -2,6 +2,7 @@
 
 namespace Illuminate\Queue\Console;
 
+use RuntimeException;
 use Illuminate\Queue\Listener;
 use Illuminate\Console\Command;
 use Symfony\Component\Console\Input\InputOption;
@@ -47,6 +48,8 @@ public function __construct(Listener $listener)
      * Execute the console command.
      *
      * @return void
+     *
+     * @throws \RuntimeException
      */
     public function fire()
     {
@@ -63,6 +66,10 @@ public function fire()
 
         $timeout = $this->input->getOption('timeout');
 
+        if ($timeout && ! function_exists('pcntl_fork')) {
+            throw new RuntimeException('Timeouts not supported without the pcntl_fork extension.');
+        }
+
         // We need to get the right queue for the connection which is set in the queue
         // configuration file for the application. We will pull it based on the set
         // connection being run for the queue operation currently being executed.