RFR: 8062247: Allow WhiteBox test to access JVM offsets

[Mikhailo Seledtsov]

Hi Yumin,

  The code looks good to me.
One minor comment: could you add explanation comment why we are using 
"ThreadToNativeFromVM ttnfv(thread);"? (no need for reposting webrev).

Thank you,
Misha

On 10/27/2014 9:01 PM, Yumin Qi wrote:
> Please review
>
> bug: https://bugs.openjdk.java.net/browse/JDK-8062247
> webrev: http://cr.openjdk.java.net/~minqi/8062247/webrev00/
>
> Summary: Internal test failed since the variable offsets changed in 
> hotspot. The way to get offset in the test is hard-coded. To reduce 
> the risk of future changes of hotspot offsets, the fix add a WhiteBox 
> API function to get a map for FileMapHeaderInfo, which return the 
> members' offsets in a Hashtable.
>
> Tests: JPRT, jtreg.
>
> Thanks
> Yumin