aosp中编译srs-server及libst报错

目前我在做的是将srs及libst源码放入android源码中交叉编译，然后集成进安卓手机中（手机CPU架构aarch64）。
android源码现在是用clang 编译。
在编译libst时，这个MD_GET_SP宏报错

#elif defined(__aarch64__)
            /* https://github.com/ossrs/state-threads/issues/9 */
            #define MD_STACK_GROWS_DOWN
            #define MD_USE_BUILTIN_SETJMP
            #define MD_GET_SP(_t) ((_t)->context[0].__jmpbuf[13])

报错内容：

system/core/libst/sched.c:616:9: error: member reference base type 'long' is not a structure or union
        _ST_INIT_CONTEXT(thread, stack->sp, _st_thread_main);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
system/core/libst/common.h:442:30: note: expanded from macro '_ST_INIT_CONTEXT'
    #define _ST_INIT_CONTEXT MD_INIT_CONTEXT
                             ^
system/core/libst/md.h:472:13: note: expanded from macro 'MD_INIT_CONTEXT'
            MD_GET_SP(_thread) = (long) (_sp);         \
            ^~~~~~~~~~~~~~~~~~
system/core/libst/md.h:429:52: note: expanded from macro 'MD_GET_SP'
            #define MD_GET_SP(_t) ((_t)->context[0].__jmpbuf[13])
                                   ~~~~~~~~~~~~~~~~^~~~~~~~~

请问这个是什么原因啊？是clang的问题吗？

Start with system/core/libst/md.h and inspect MD_GET_SP and the AArch64 context definition used by Android's clang. Trace the expansion from system/core/libst/sched.c through common.h and md.h, then compare the expected type of context[0].__jmpbuf[13]. Done means identifying the cause and documenting a compatible resolution for the AArch64 Android build.