8254239: G1ConcurrentMark.hpp unnecessarily disables MSVC++ warning 4522.

Reviewed-by: iklam, kbarrett

Author: vshining

src/hotspot/share/gc/g1/g1ConcurrentMark.hpp

@@ -50,10 +50,6 @@ class G1RegionToSpaceMapper;
 class G1SurvivorRegions;
 class ThreadClosure;
 
-PRAGMA_DIAG_PUSH
-// warning C4522: multiple assignment operators specified
-PRAGMA_DISABLE_MSVC_WARNING(4522)
-
 // This is a container class for either an oop or a continuation address for
 // mark stack entries. Both are pushed onto the mark stack.
 class G1TaskQueueEntry {
@@ -89,8 +85,6 @@ class G1TaskQueueEntry {
   bool is_null() const { return _holder == NULL; }
 };
 
-PRAGMA_DIAG_POP
-
 typedef GenericTaskQueue<G1TaskQueueEntry, mtGC> G1CMTaskQueue;
 typedef GenericTaskQueueSet<G1CMTaskQueue, mtGC> G1CMTaskQueueSet;