[单片机框架][esp32] 使用C++17新特性报错

1. 修改CMakeLists.txt ，追加-std=gnu++17

# For more information about build system see
# https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/build-system.html
# The following five lines of boilerplate have to be in your project's
# CMakeLists in this exact order for cmake to work correctly
cmake_minimum_required(VERSION 3.5)

include($ENV{IDF_PATH}/tools/cmake/project.cmake)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-missing-field-initializers -funsigned-char -w -Wfatal-errors -Wno-unused-variable -std=gnu++17")
project(main)

2. 修改cmake编译文件，路径x:\Espressif\esp-idf\tools\cmake\build.cmake