RFR: 8293841: RISC-V: Implementation of Foreign Function & Memory API (Preview) [v4]

[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 incrementally with one additional commit since the last revision:

  fix callArranger

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/11004/files
  - new: https://git.openjdk.org/jdk/pull/11004/files/289b8697..fd312661

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11004&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11004&range=02-03

  Stats: 6 lines in 2 files changed: 0 ins; 2 del; 4 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