8283929: GHA: Add RISC-V build config

[gnu-andrew]

JDK-8199138 was added to 11u back in 2021 to allow Zero to support RISC-V, but it wasn't added to the GHA cross compile testing so we have no idea if it actually builds or gets broken by patches. This came to my intention when looking at the proposal to add RISC-V Zero support to 8u

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Progress

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Integration blocker

 ⚠️ Dependency #3196 must be integrated first

Issue

• JDK-8283929: GHA: Add RISC-V build config (Enhancement - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk11u-dev.git pull/3205/head:pull/3205
$ git checkout pull/3205

Update a local copy of the PR:
$ git checkout pull/3205
$ git pull https://git.openjdk.org/jdk11u-dev.git pull/3205/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 3205

View PR using the GUI difftool:
$ git pr show -t 3205

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk11u-dev/pull/3205.diff

[bridgekeeper]

👋 Welcome back andrew! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[gnu-andrew]

Looks like this will need the bump to trixie first.