[riscv-port] RFR: 8278387: riscv: Implement UseHeavyMonitors consistently

[Yadong Wang]

Make hotspot always use inflated monitors consistently if the flag UseHeavyMonitors is true. The riscv platform should follow https://bugs.openjdk.java.net/browse/JDK-8276901.

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Commit messages:
- 8278387: riscv: Implement UseHeavyMonitors consistently

Changes: https://git.openjdk.java.net/riscv-port/pull/26/files
Webrev: https://webrevs.openjdk.java.net/?repo=riscv-port&pr=26&range=00
Issue: https://bugs.openjdk.java.net/browse/JDK-8278387
Stats: 129 lines in 6 files changed: 40 ins; 20 del; 69 mod
Patch: https://git.openjdk.java.net/riscv-port/pull/26.diff
Fetch: git fetch https://git.openjdk.java.net/riscv-port pull/26/head:pull/26

PR: https://git.openjdk.java.net/riscv-port/pull/26