compiler: add go test command

_demo/runtest/main.go

@@ -0,0 +1,16 @@
+package main
+
+import (
+	"github.com/goplus/llgo/_demo/runtest/bar"
+	"github.com/goplus/llgo/_demo/runtest/foo"
+)
+
+func Zoo() int {
+	return 3
+}
+
+func main() {
+	println("foo.Foo()", foo.Foo())
+	println("bar.Bar()", bar.Bar())
+	println("Zoo()", Zoo())
+}