RFR: 8199067 [REDO] NMT: Enhance thread stack tracking

[Zhengyu Gu]

The early change failed on some fast machine with many processors 
running Linux OS. It reveals that there can be holes in thread's stack, 
which throws off binary search for finding stack bottom.

Besides, some threads (ConcurrentGCThread and WatcherThread, etc.) do 
exit without notifying NMT, which can trip over NMT final reporting, as 
their stacks became unmapped.

This patch addresses above issues by searching whole address range for 
committed regions. If the address range becomes invalid, simply reports 
as not committed.

GTest also updated.

Bug: https://bugs.openjdk.java.net/browse/JDK-8199067
Webrev: http://cr.openjdk.java.net/~zgu/8199067/webrev.00/index.html


Test:
   hotspot tier1 on Linux 64 and Windows x64.

   Submit repo test came back clean.
   Mach5 mach5-one-zgu-JDK-8199067-20180308-1218-13719: Builds PASSED. 
Testing SUCCESSFUL.


Thanks,

-Zhengyu