RFR: 7903732: Verify that the java executable exists

[Christian Stein]

On Wed, 22 May 2024 12:51:03 GMT, Ludvig Janiuk <lujaniuk at openjdk.org> wrote:

> I want to add a small check in `src/share/bin/jtreg.sh` to have jtreg see if the java it wants to run even exists, before proceeding to verify the version. This would make it easier for the user to notice tha they have mistyped the -jdk parameter.

Failing faster with a better error message is good.

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Marked as reviewed by cstein (Committer).

PR Review: https://git.openjdk.org/jtreg/pull/196#pullrequestreview-2076588192