Fix handling of IPC::Run::run exit status

Turns out that the exit status is returned in $?, not as the return
value of run().  So our error checking was completely bogus.

src/lib/Hydra/Controller/Admin.pm

@@ -424,7 +424,7 @@ sub force_eval : Chained('admin') Path('eval') Args(2) {
     $c->stash->{jobset} = $c->stash->{jobset_}->single
         or notFound($c, "Jobset $jobsetName doesn't exist.");
 
-    (my $res, my $stdout, my $stderr) = captureStdoutStderr(60, ("hydra-evaluator", $projectName, $jobsetName));
+    captureStdoutStderr(60, "hydra-evaluator", $projectName, $jobsetName);
 
     $c->res->redirect("/project/$projectName");
 }