git: openjdk/jdk-sandbox: riscv-port-branch: Implement index() method in Address class for riscv port.

[duke]

Changeset: 5ca81b9b
Author:    Fei Yang <felix.yang at huawei.com>
Date:      2021-10-26 02:26:14 +0000
URL:       https://git.openjdk.java.net/jdk-sandbox/commit/5ca81b9b83d83f384045464f4670f1299ff37ad5

Implement index() method in Address class for riscv port.
We can revert code changes in file zBarrierSetC2.cpp with this change.

! src/hotspot/cpu/riscv/assembler_riscv.hpp
! src/hotspot/share/c1/c1_LIR.cpp
! src/hotspot/share/gc/z/c2/zBarrierSetC2.cpp