RFR: Add path independence

[Per Minborg]

On Wed, 31 Aug 2022 07:15:33 GMT, Per Minborg <duke at openjdk.org> wrote:

> This small PR incorporated feedback from the original PR: https://github.com/openjdk/jextract/pull/66 made after it was integrated.

Perhaps we could mention a specific version in the README file (e.g. the example here is verified for foo version x.y.z) and that appropriate changes might have to be made if another version is used.

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PR: https://git.openjdk.org/jextract/pull/68