checker: add -skip-unused support for vweb.run_at too (#18884)

vlib/v/checker/fn.v

@@ -2261,7 +2261,7 @@ fn (mut c Checker) post_process_generic_fns() ! {
 		for concrete_types in gtypes {
 			c.table.cur_concrete_types = concrete_types
 			c.fn_decl(mut node)
-			if node.name == 'vweb.run' {
+			if node.name in ['vweb.run', 'vweb.run_at'] {
 				for ct in concrete_types {
 					if ct !in c.vweb_gen_types {
 						c.vweb_gen_types << ct

vlib/v/tests/skip_unused/vweb_run_at.run.out

@@ -0,0 +1,3 @@
+[Vweb] Running app on http://localhost:38090/
+[Vweb] We have 1 workers
+done

vlib/v/tests/skip_unused/vweb_run_at.skip_unused.run.out

@@ -0,0 +1,3 @@
+[Vweb] Running app on http://localhost:38090/
+[Vweb] We have 1 workers
+done

vlib/v/tests/skip_unused/vweb_run_at.vv

@@ -0,0 +1,21 @@
+import vweb
+import time
+
+struct App {
+	vweb.Context
+}
+
+fn main() {
+	spawn fn () {
+		time.sleep(100 * time.millisecond)
+		println('done')
+		exit(0)
+	}()
+	vweb.run_at(&App{}, port: 38090, nr_workers: 1)!
+	//	vweb.run(&App{}, 38091)
+}
+
+['/']
+pub fn (mut app App) app_main() vweb.Result {
+	return app.text('Hello World')
+}