Fix compilation error on Windows

The issue was caused by conflicting declaration of HKEY
happening in our WM code and somewhere deeper in atomic
operations headers hierarchy.

source/blender/compositor/intern/COM_ExecutionGroup.cpp

@@ -25,6 +25,8 @@
 #include <sstream>
 #include <stdlib.h>
 
+#include "atomic_ops.h"
+
 #include "COM_ExecutionGroup.h"
 #include "COM_defines.h"
 #include "COM_ExecutionSystem.h"
@@ -44,8 +46,6 @@
 #include "WM_api.h"
 #include "WM_types.h"
 
-#include "atomic_ops.h"
-
 ExecutionGroup::ExecutionGroup()
 {
 	this->m_isOutput = false;