[12] RFR: 8208499 NMT: Missing memory tag for Safepoint polling page

[Zhengyu Gu]

Hi,

Could I have reviews for this small fix to add missing memory tag for 
global safepoint polling page?

I added "Safepoint" memory type, as a part of effort to fine grain the 
memory types [1]


Bug: https://bugs.openjdk.java.net/browse/JDK-8208499
Webrev: http://cr.openjdk.java.net/~zgu/8208499/webrev.00/index.html


Test:

   hotspot_nmt on Linux 64 (fastdebug and release)

[1] JDK-8199746 NMT: Breakup overused mtInternal into more fine grained 
categories.

Thanks,

-Zhengyu