Fix traversal of dirs containing troublesome softlinks (#1718)

Fix traversal of dirs containing troublesome softlinks (#1718)

* Fix enumeration of files with troublesome softlinks

* Self-review

* Workaround in `den` for GCC 14 C++ bug

* 2nd self-review

commit 7d8b2ccd77998bbc0adfea8807b1ecea19a2a332
Author: Alejandro R. Mosteo <amosteo@unizar.es>
Date:   Fri Aug 2 09:53:22 2024 +0200

    Debug trouble with relative path finder

commit 09514571571d234a19af3eee5202838e85508c60
Author: Alejandro R. Mosteo <amosteo@unizar.es>
Date:   Thu Aug 1 22:32:48 2024 +0200

    Use simpler relative path from Den

commit 76417fa28f0daf0c0244129c9fecc2d6db7abc37
Author: Alejandro R. Mosteo <amosteo@unizar.es>
Date:   Thu Aug 1 22:32:09 2024 +0200

    Revert "Try with gprbuild<24"

    This reverts commit b6ca84eac4e7af62aedd2e8d73545da0c71b9fb1.

commit f6e0a963163a517b56a17243f1e2685263d7e244
Author: Alejandro R. Mosteo <amosteo@unizar.es>
Date:   Thu Aug 1 00:04:00 2024 +0200

    Repair find relative part output

commit 6ad595ff4de348b72d894339b7172c8797a7bf64
Author: Alejandro R. Mosteo <amosteo@unizar.es>
Date:   Wed Jul 31 23:28:48 2024 +0200

    Flush testsuite output at start

commit a52e5555983b94adb0090869e0e67c40a8bb9b4c
Author: Alejandro R. Mosteo <amosteo@unizar.es>
Date:   Wed Jul 31 18:18:44 2024 +0200

    Fix damaged test

commit b6ca84eac4e7af62aedd2e8d73545da0c71b9fb1
Author: Alejandro R. Mosteo <amosteo@unizar.es>
Date:   Wed Jul 31 14:16:11 2024 +0200

    Try with gprbuild<24

commit 500021055430ddc56ca8d4bfbfb371d6e1434333
Author: Alejandro R. Mosteo <amosteo@unizar.es>
Date:   Wed Jul 31 14:04:07 2024 +0200

    Show GNAT/GPRBUILD versions prior to testsuite run