message: fix race condition in tasking::schedule() unit test (use crude spin lock)
diff: #include "../schedule.h"
  #include <atomic>
  -#include <chrono>
  -#include <condition_variable>
  -#include <mutex>
  using ospcommon::tasking::schedule;
  TEST_CASE("async")
  {
  std::atomic<int> val{0};
  - std::mutex mutex;
  - std::condition_variable condition;
  auto *val_p = &val;
  - auto *cond_p = &condition;
  schedule([=](){
  *val_p = 1;
  - cond_p->notify_all();
  });
  - std::unique_lock<std::mutex> lock(mutex);
  - auto now = std::chrono::system_clock::now();
  - condition.wait_until(lock,
  - now + std::chrono::seconds(3),
  - [&](){ return val.load() == 1; });
  + while (val.load() == 0);
  - // NOTE(jda) - can't directly check std::atomic value due to compile error...
  - int check_val = val;
  - REQUIRE(check_val == 1);
  + REQUIRE(val.load() == 1);
  }
  