RFR: 8348387: Add fixpath if needed for user-supplied tools

[Erik Joelsson]

On Thu, 23 Jan 2025 10:02:32 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

> When discovering tools, configure checks if it is a program that can handle unix-style paths or not. If it isn't, a fixpath prefix is automatically added.
> 
> But when the user supplies a tool like `configure FOO=foo.exe`, this does not happen. If that tool does not understand unix-style paths, then it will fail, and there is no easy way for the user to fix this.
> 
> Instead, we should apply the fixpath check also to user-supplied tools.

Marked as reviewed by erikj (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/23257#pullrequestreview-2569915444