Method __sp_mut

system/lib/libcxx/src/memory.cpp:114–114

    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER};

constexpr __sp_mut::__sp_mut(void* p) noexcept : __lx_(p) {}

void __sp_mut::lock() noexcept {
  auto m = static_cast<__libcpp_mutex_t*>(__lx_);