添加对g711A/U rtsp支持相关文件，api添加windows静态库编译选项，g711 RTMP支持尚未修改

src/Extension/G711.cpp

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2016 The ZLMediaKit project authors. All Rights Reserved.
+ *
+ * This file is part of ZLMediaKit(https://github.com/xiongziliang/ZLMediaKit).
+ *
+ * Use of this source code is governed by MIT license that can be found in the
+ * LICENSE file in the root of the source tree. All contributing project authors
+ * may be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "G711.h"
+
+namespace mediakit{
+
+
+Sdp::Ptr G711Track::getSdp() {
+    if(!ready()){
+        WarnL << "AAC Track未准备好";
+        return nullptr;
+    }
+    return std::make_shared<G711Sdp>(getCodecId(), getAudioSampleRate(), getCodecId() == CodecG711A ? 8 : 0, getAudioSampleBit());
+}
+
+}//namespace mediakit
+
+