[core] Fixed C++11 build (win)

[maxsharabayko]

Fixed some places where pthreads was still in use.

TODO

• Handle the case if (pthread_equal(pthread_self(), m_WorkerThread))

[maxsharabayko]

A test case just to confirm srt::sync::CThread::id::operator==(..) is called properly.

void* func(void* th)
{
    CThread* thread = reinterpret_cast<CThread*>(th);
    cout << "Thread check. Expected true. Result: " << (thread->get_id() == srt::sync::this_thread::get_id()) << endl;
    return NULL;
}

TEST(SyncThread, OperatorCompare)
{
    CThread th;
    StartThread(th, &func, (void*) &th, "Name");
    cout << "Main check. Expected false. Result: " << (th.get_id() == srt::sync::this_thread::get_id()) << endl;

    th.join();
}