git: openjdk/jdk21u: master: 8319525: RISC-V: Rename *_riscv64.ad files to *_riscv.ad under riscv/gc

[Fei Yang]

Changeset: 7091631c
Author:    Fei Yang <fyang at openjdk.org>
Date:      2023-11-08 13:18:53 +0000
URL:       https://git.openjdk.org/jdk21u/commit/7091631c5f216765f19c57825bb9e9ee0af428d3

8319525: RISC-V: Rename *_riscv64.ad files to *_riscv.ad under riscv/gc

Backport-of: b2504a0f9cff1f4fdf8f5bb20c4b48a53ba0be77

= src/hotspot/cpu/riscv/gc/shenandoah/shenandoah_riscv.ad
= src/hotspot/cpu/riscv/gc/x/x_riscv.ad
= src/hotspot/cpu/riscv/gc/z/z_riscv.ad