[8u-dev] backport RFR: 6869327: Add new C2 flag to keep safepoints in counted loops

[Andreas Eriksson]

Hi,

Please review this backport of JDK-6869327: Add new C2 flag to keep 
safepoints in counted loops.
The only change in this backport is to the test, where the testlibrary 
imports needed to be changed, and I also removed the @module tag.

JDK 9 review: 
http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2015-November/020110.html

Webrev for changes between 9 and 8:
http://cr.openjdk.java.net/~aeriksso/6869327/webrev.9_to_8/

Full 8u webrev:
http://cr.openjdk.java.net/~aeriksso/6869327/webrev.jdk8u/

Bug: 6869327: Add new C2 flag to keep safepoints in counted loops.
https://bugs.openjdk.java.net/browse/JDK-6869327

Thanks,
Andreas