[jdk17u-dev] RFR: 8318953: RISC-V: Small refactoring for MacroAssembler::test_bit

[Gui Cao]

Hi, this backport to make the test_bit assember function more simpler and to improve performance when the parameter (1UL << bit_pos) exceeds 32-bit range. This is a risc-v specific change. Backport is clean, risk is low.
By the way, fastlock needs to call test_bit, because in the mainline version, the fastlock function is extracted to c2_MacroAssembler_riscv.cpp, but in jdk17u-dev, fastlock is still in riscv.ad, so PR is not in clean state.
### Testing:
qemu 8.1.50:
- [ ] Tier1 tests (release)

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Commit messages:
 - Backport 8318953: RISC-V: Small refactoring for MacroAssembler::test_bit

Changes: https://git.openjdk.org/jdk17u-dev/pull/1941/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1941&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8318953
  Stats: 10 lines in 3 files changed: 6 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1941.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1941/head:pull/1941

PR: https://git.openjdk.org/jdk17u-dev/pull/1941