test(build):collect llgo test ./... output to test

cl/_testgo/runextest/bar/bar_test.go

@@ -0,0 +1,13 @@
+package bar_test
+
+import (
+	"testing"
+
+	"github.com/goplus/llgo/cl/_testgo/runextest/bar"
+)
+
+func TestBar(t *testing.T) {
+	if bar.Bar() != 2 {
+		t.Fatal("Bar() != 2")
+	}
+}