[riscv-port-jdk11u:riscv-port] RFR: 8283929: GHA: Add RISC-V build config

[Fei Yang]

On Wed, 21 Feb 2024 13:27:14 GMT, Gui Cao <gcao at openjdk.org> wrote:

> Backport [JDK-8283929](https://bugs.openjdk.org/browse/JDK-8283929), [JDK-8313701](https://bugs.openjdk.org/browse/JDK-8313701)  and [JDK-8285630](https://bugs.openjdk.org/browse/JDK-8285630) to enable GHA cross-compiling for linux-riscv64 on riscv-port-jdk11u repo.

BTW: The ops has reconfigured this repo (and friends) so that GHA test results will be displayed on PRs against it. Now I see it's working for this PR :-)

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PR Comment: https://git.openjdk.org/riscv-port-jdk11u/pull/6#issuecomment-1959613027