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

cl/_testgo/runextest/foo/foo_test.go

@@ -0,0 +1,13 @@
+package foo_test
+
+import (
+	"testing"
+
+	"github.com/goplus/llgo/cl/_testgo/runextest/foo"
+)
+
+func TestFoo(t *testing.T) {
+	if foo.Foo() != 1 {
+		t.Fatal("Foo() != 1")
+	}
+}