Disable warnings in the standard gdiplus.h header with MSVC14.

There is nothing we can do about these (harmless) warnings, so just disable
them.

(cherry picked from commit a2d6341e4f)

include/wx/msw/wrapgdip.h

@@ -24,8 +24,21 @@
     #define min(a,b)            (((a) < (b)) ? (a) : (b))
 #endif
 
+// There are many clashes between the names of the member fields and parameters
+// in the standard gdiplus.h header and each of them results in C4458 with
+// VC14, so disable this warning for this file as there is no other way to
+// avoid it.
+#ifdef __VISUALC__
+    #pragma warning(push)
+    #pragma warning(disable:4458) // declaration of 'xxx' hides class member
+#endif
+
 #include <gdiplus.h>
 using namespace Gdiplus;
 
+#ifdef __VISUALC__
+    #pragma warning(pop)
+#endif
+
 #endif // _WX_MSW_WRAPGDIP_H_