[8u40] RFR(M) 8041984: CompilerThread seems to occupy all CPU in a very rare situation

[Vladimir Kozlov]

Backport request. Changes were pushed into jdk9 last week. Nighties are 
fine. Changes are applied cleanly to 8u sources.

https://bugs.openjdk.java.net/browse/JDK-8041984
http://cr.openjdk.java.net/~kvn/8041984/webrev.01/

Review thread:
http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2014-October/015855.html

jdk9 changeset:
http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/b9576378eaad

Thanks,
Vladimir