[riscv-port-jdk11u:riscv-port] RFR: 8291893: riscv: remove fence.i used in user space [v3]

[Gui Cao]

> Please help review this backport to riscv-port-jdk11u.
> Backport of [JDK-8291893](https://bugs.openjdk.org/browse/JDK-8291893)
> 
> In addition to the backport [8291947](https://bugs.openjdk.org/browse/JDK-8291947), [8310656](https://bugs.openjdk.org/browse/JDK-8310656) to align and minimize the difference with 17u upstream.
> 
> Testing:
> 
> - [x] Run tier1-3 tests on SOPHON SG2042 (release)

Gui Cao has updated the pull request incrementally with one additional commit since the last revision:

  Add extra include header

-------------

Changes:
  - all: https://git.openjdk.org/riscv-port-jdk11u/pull/16/files
  - new: https://git.openjdk.org/riscv-port-jdk11u/pull/16/files/6db0c80f..383fd357

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=riscv-port-jdk11u&pr=16&range=02
 - incr: https://webrevs.openjdk.org/?repo=riscv-port-jdk11u&pr=16&range=01-02

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/riscv-port-jdk11u/pull/16.diff
  Fetch: git fetch https://git.openjdk.org/riscv-port-jdk11u.git pull/16/head:pull/16

PR: https://git.openjdk.org/riscv-port-jdk11u/pull/16