use pragma warning push/pop under MSVC instead of enabling temporarily disabled warnings unconditionally (patch 1207689)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@34565 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/rawbmp.h

@@ -73,6 +73,7 @@
 
 #ifdef __VISUALC__
     // VC++ gives an absolutely harmless warning for wxPixelData<wxBitmap> ctor
+    #pragma warning(push)
     #pragma warning(disable: 4355) // 'this' used in initializer list
 #endif
 
@@ -717,8 +718,7 @@ struct wxPixelIterator : wxPixelData<Image, PixelFormat>::Iterator
 };
 
 #ifdef __VISUALC__
-    #pragma warning(default: 4355)
-    #pragma warning(default: 4097)
+    #pragma warning(pop)
 #endif
 
 #endif // _WX_RAWBMP_H_BASE_