RFR: 8216154: C4819 warnings at HotSpot sources on Windows

[Kim Barrett]

> On Jan 6, 2019, at 12:54 PM, Kim Barrett <kim.barrett at oracle.com> wrote:
> 
>> On Jan 6, 2019, at 7:53 AM, Yasumasa Suenaga <yasuenag at gmail.com> wrote:
>> 
>> Hi Kim,
>> 
>> Thank you for your comment.
>> I uploaded new webrev to use pragma warning push/pop:
>> 
>> http://cr.openjdk.java.net/~ysuenaga/JDK-8216154/webrev.01/
>> 
>> 
>> Please review again.
> 
> Looks good.

It later occurred to me to wonder whether _WINDOWS was the right macro to conditionalize
on.  All other uses of #pragma warning push/pop (there are 5 in HotSpot) use _MSC_VER.

I also wonder why we don’t have a Visual Studio definition for PRAGMA_DIAG_PUSH/POP,
but that’s a different issue altogether.