Fix Wreorder warning coming from AccessorSubscript constructor

Author: AlexeySachkov

sycl/include/sycl/accessor.hpp

@@ -336,7 +336,7 @@ class accessor_common {
 
   public:
     AccessorSubscript(AccType Accessor, id<Dims> IDs)
-        : MAccessor(Accessor), MIDs(IDs) {}
+        : MIDs(IDs), MAccessor(Accessor) {}
 
     // Only accessor class is supposed to use this c'tor for the first
     // operator[].