Retire FakeSplit

- Currently broken
    - Never been really useful
    - Does not work well with new splitting model

Verified for no regression at STC with 3 threads:
LLR: 2.96 (-2.94,2.94) [-6.00,0.00]
Total: 81905 W: 12122 L: 12381 D: 57402

No functional change

src/search.cpp

@@ -52,9 +52,6 @@ using namespace Search;
 
 namespace {
 
-  // Set to true to force running with one thread. Used for debugging
-  const bool FakeSplit = false;
-
   // Different node types, used as template parameter
   enum NodeType { Root, PV, NonPV };
 
@@ -987,7 +984,7 @@ moves_loop: // When in check and at SpNode search starts from here
       {
           assert(bestValue > -VALUE_INFINITE && bestValue < beta);
 
-          thisThread->split<FakeSplit>(pos, ss, alpha, beta, &bestValue, &bestMove,
+          thisThread->split(pos, ss, alpha, beta, &bestValue, &bestMove,
                             depth, moveCount, &mp, NT, cutNode);
 
           if (Signals.stop || thisThread->cutoff_occurred())

src/thread.cpp

@@ -255,7 +255,6 @@ Thread* ThreadPool::available_slave(const Thread* master) const {
 // leave their idle loops and call search(). When all threads have returned from
 // search() then split() returns.
 
-template <bool Fake>
 void Thread::split(Position& pos, const Stack* ss, Value alpha, Value beta, Value* bestValue,
                    Move* bestMove, Depth depth, int moveCount,
                    MovePicker* movePicker, int nodeType, bool cutNode) {
@@ -297,7 +296,6 @@ void Thread::split(Position& pos, const Stack* ss, Value alpha, Value beta, Valu
   activeSplitPoint = &sp;
   activePosition = NULL;
 
-  if (!Fake)
   for (Thread* slave; (slave = Threads.available_slave(this)) != NULL; )
   {
       sp.slavesMask.set(slave->idx);
@@ -339,11 +337,6 @@ void Thread::split(Position& pos, const Stack* ss, Value alpha, Value beta, Valu
   Threads.mutex.unlock();
 }
 
-// Explicit template instantiations
-template void Thread::split<false>(Position&, const Stack*, Value, Value, Value*, Move*, Depth, int, MovePicker*, int, bool);
-template void Thread::split< true>(Position&, const Stack*, Value, Value, Value*, Move*, Depth, int, MovePicker*, int, bool);
-
-
 // wait_for_think_finished() waits for main thread to go to sleep then returns
 
 void ThreadPool::wait_for_think_finished() {

src/thread.h

@@ -117,7 +117,6 @@ struct Thread : public ThreadBase {
   bool cutoff_occurred() const;
   bool available_to(const Thread* master) const;
 
-  template <bool Fake>
   void split(Position& pos, const Search::Stack* ss, Value alpha, Value beta, Value* bestValue, Move* bestMove,
              Depth depth, int moveCount, MovePicker* movePicker, int nodeType, bool cutNode);