Request for review(XS): 7005241: C1: SEGV in java.util.concurrent.LinkedTransferQueue.xfer() with compressed oops

[Igor Veresov]

Implementation of the CAS primitive for x64 compressed oops was 
incorrect. It kills rscratch2 register (r11), which is allocatable in 
C1. Also, we don't need to restore cmpval as it's never used after that, 
so we need only one temporary register, which can be scratch1.

Webrev: http://cr.openjdk.java.net/~iveresov/7005241/webrev.00

Tested with the failed nightly test.

Thanks,
igor