RFR 8232992: Shenandoah: Implement self-fixing interpreter LRB

[Zhengyu Gu]

Please review this patch that implements self-fixing interpreter LRB.


Bug: https://bugs.openjdk.java.net/browse/JDK-8232992
Webrev: http://cr.openjdk.java.net/~zgu/JDK-8232992/webrev.00/

Test:
   hotspot_gc_shenandoah (fastdebug and release)
   x86_64 and x86_32 on Linux
   aarch64 Linux
   Windows x86_64

Thanks,

-Zhengyu