[libffi] add risc-v support

[dtcxzyw]

Add risc-v support for libffi. Tested with Ubuntu 22.04.1 LTS (GNU/Linux 5.19.0-1012-generic riscv64).

• Changes comply with the maintainer guide
• SHA512s are updated for each updated download
• The "supports" clause reflects platforms that may be fixed by this new version
• Any fixed CI baseline entries are removed from that file.
• Any patches that are no longer applied are deleted from the port's directory.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is added to each modified port's versions file.

[Adela0814]

Thank you for submitting this PR, CI has no relevant machine to test risc-v. Please make sure your changes have been tested locally.

[dtcxzyw]

Thank you for submitting this PR, CI has no relevant machine to test risc-v. Please make sure your changes have been tested locally.

It works on my risc-v machine.

• OS: Ubuntu 22.04.1 LTS (GNU/Linux 5.19.0-1012-generic riscv64)
• Compiler: gcc 11.3.0 riscv64-linux-gnu
• CPU: SiFive U74-MC