feat(esp8266): Add WIFI socket and async APIs

1. add section to linking file

components/esp8266/include/net/if_socket.h

@@ -0,0 +1,76 @@
+// Copyright 2018 Espressif Systems (Shanghai) PTE LTD
+//
+// 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.
+
+#ifndef _IF_ETHER_H
+#define _IF_ETHER_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * undefine some global macro
+ */
+#undef ETH_P_ALL
+#undef ETH_P_ARP
+#undef ETH_P_IP
+
+#undef AF_PACKET
+
+#undef SOCK_RAW
+
+/*
+ * socket domain
+ */
+#define AF_PACKET 0
+
+/*
+ * socket type
+ */
+#define SOCK_RAW 0
+
+/*
+ * use 16(2^4) type for socket
+ */ 
+#define IF_SOCK_SHIFT           4
+#define IF_SOCK_TYPE(d)         (d & 0xf)
+#define IF_SOCK_DATA(t, s)      ((1 << (s + IF_SOCK_SHIFT)) + t)
+
+enum if_sock_type {
+    IF_SOCK_ETH = 0,
+    IF_SOCK_WIFI,
+
+    IF_SOCK_MAX,
+};
+
+#define IF_ETH_DATA(s)          IF_SOCK_DATA(IF_SOCK_ETH, s)
+#define IF_WIFI_DATA(s)         IF_SOCK_DATA(IF_SOCK_WIFI, s)
+
+/*
+ * socket protocol
+ */
+#define ETH_P_IP                IF_ETH_DATA(0)
+#define ETH_P_ARP               IF_ETH_DATA(1)
+#define ETH_P_ALL               ETH_P_IP | ETH_P_ARP
+
+#define WIFI_P_MNG              IF_WIFI_DATA(0)
+#define WIFI_P_CTL              IF_WIFI_DATA(1)
+#define WIFI_P_DAT              IF_WIFI_DATA(2)
+#define WIFI_P_ALL              WIFI_P_MNG | WIFI_P_CTL | WIFI_P_DAT
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _IF_ETHER_H */