#### 为什么提交这份PR (why to submit this PR) - 修复ch32v307v-r1 board.h 中变量_stack_size未声明BUG - 提供ch32v307v-r1动态堆内存分配(宏开关)代码 - ch32v307v-r1 MD文档新增烧录方式,作为烧录后无运行结果的替代方案 #### 你的解决方案是什么 (what is your solution) - 去掉_stack_size未声明变量 - 动态分配内存堆,将堆起始地址放在.bss段结尾,堆结束地址放在.stack段开头[详情](https://club.rt-thread.org/ask/article/001065082e9ae611.html) - 将烧录工具替换为WCH-LinkUtility #### 在什么测试环境下测试通过 (what is the test environment) - 开发工具: RT-Thread Studio - 测试板卡:ch32v307v-r1评估板 - 烧录工具:WCH-LinkUtility
* [rtdef] rename RT_WEAK attribute as rt_weak * [rtdef] rename RT_USED attribute as rt_used * [rtdef] rename RT_SECTION attribute as rt_section * [rtdef] rename ALIGN attribute as rt_align * [legacy] add RT_USED ALIGN RT_SECTION RT_WEAK as legacy support