RFR: 8293841: RISC-V: Implementation of Foreign Function & Memory API (Preview) [v2]

[Feilong Jiang]

> Add experimental Foreign Function & Memory API support for RISC-V.
> 
> For details of the FFM API RISC-V port please refer to [JBS issue](https://bugs.openjdk.org/browse/JDK-8293841)
> 
> Testing:
> 
> - [x] jdk_foreign with release/fastdebug build
> - [x] run TestMatrix.java manually with release/fastdebug build

Feilong Jiang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Merge branch 'master' of https://github.com/openjdk/jdk into JDK-8293841-foreign-api-riscv
 - code adjustment and remove unnecessary static
 - sync with JDK-8296477
 - sync with JDK-8295044
 - JDK-8293841: RISC-V: Implementation of Foreign Function & Memory API (Preview)

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/11004/files
  - new: https://git.openjdk.org/jdk/pull/11004/files/c155840c..efe8238e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11004&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11004&range=00-01

  Stats: 6771 lines in 356 files changed: 3498 ins; 2172 del; 1101 mod
  Patch: https://git.openjdk.org/jdk/pull/11004.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11004/head:pull/11004

PR: https://git.openjdk.org/jdk/pull/11004