artf4107: GetInstance() calls are now atomic

C++11 guarantees construction of static variables to be atomic, so this patch takes advantage of that.

Change-Id: I4a3db0f19c5fa5461fef3b6b63d7b8fec596c962

wpilibc/wpilibC++/src/Commands/Scheduler.cpp

@@ -16,8 +16,6 @@
 #include <set>
 #include <algorithm>
 
-Scheduler *Scheduler::_instance = nullptr;
-
 Scheduler::Scheduler() {
   m_buttonsLock = initializeMutexNormal();
   m_additionsLock = initializeMutexNormal();
@@ -38,8 +36,8 @@ Scheduler::~Scheduler() {
  * @return the {@link Scheduler}
  */
 Scheduler *Scheduler::GetInstance() {
-  if (_instance == nullptr) _instance = new Scheduler();
-  return _instance;
+  static Scheduler instance;
+  return &instance;
 }
 
 void Scheduler::SetEnabled(bool enabled) { m_enabled = enabled; }