RFR: 8326375: [REDO] Clean up NativeCompilation.gmk and its newly created parts

[Erik Joelsson]

On Wed, 21 Feb 2024 11:36:34 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

> This is a redo of [JDK-8325963](https://bugs.openjdk.org/browse/JDK-8325963). The original patch caused problems on the Oracle internal CI system, and was backed out.
> 
> The difference in this patch is that `GetEntitlementsFile` can now work stand-alone if called from a custom makefile. This can be seen in a [separate commit](https://github.com/openjdk/jdk/pull/17946/commits/394bb7c2994b59e1cf977fc5e664643d0a365f78) for ease of reviewing.

Marked as reviewed by erikj (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/17946#pullrequestreview-1893231000