RFR: 8284584: Avoid duplicate node_idx_t definitions [v2]

[Claes Redestad]

On Wed, 13 Apr 2022 09:57:01 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> While looking at `Node`, I realized there are two definitions for node_idx_t, another one added by [JDK-8076284](https://bugs.openjdk.java.net/browse/JDK-8076284). These should be de-duplicated to avoid confusion.
>
> Aleksey Shipilev 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 three additional commits since the last revision:
> 
>  - Leave one definition in compile.hpp only
>  - Merge branch 'master' into JDK-8284584-node-idx-duplicate
>  - Move

Looks good and trivial

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Marked as reviewed by redestad (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/8164