[8u] RFR 8065895: Synchronous signals during error reporting may terminate or hang VM process

[Zhengyu Gu]

I would like to backport this patch to openjdk8u for parity with Oracle 
8u321.

Bug: https://bugs.openjdk.java.net/browse/JDK-8065895
jdk9 patch: http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/6bfc40057b3f


jdk9 patch does not apply cleanly. There is only one conflict in 
debug.cpp, due to line shifts.

8u webrev: http://cr.openjdk.java.net/~zgu/JDK-8065895-8u/webrev.00/


Thanks,

-Zhengyu