examples/flappy: add main_cbackend.go

examples/flappy/main_cbackend.go

@@ -0,0 +1,29 @@
+// Copyright 2021 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build example && ebitencbackend
+// +build example,ebitencbackend
+
+// This file is for some special environments using `ebitencbackend`.
+// You usually don't have to care about this file.
+// Actually this example works without this file in usual cases.
+
+package main
+
+import "C"
+
+//export GoMain
+func GoMain() {
+	main()
+}