feat(gcc): update cross toolchain GCC to v8.x

components/newlib/platform_include/sys/uio.h

@@ -0,0 +1,21 @@
+// Copyright 2019-2020 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 _ESP_PLATFORM_SYS_UIO_H_
+#define _ESP_PLATFORM_SYS_UIO_H_
+
+int writev(int s, const struct iovec *iov, int iovcnt);
+
+ssize_t readv(int fd, const struct iovec *iov, int iovcnt);
+
+#endif // _ESP_PLATFORM_SYS_UIO_H_