RFR: 8355400: Better git detection in update_copyright_year.sh

[duke]

On Wed, 23 Apr 2025 13:19:19 GMT, Manuel Hässig <duke at openjdk.org> wrote:

> The script `make/scripts/update_copyright.sh` relies on the path to the script for git detection, which is fragile or does not work at all or git worktrees. This PR uses git itself to detect whether the script is running in a git repository. This has the added benefit that the script can be executed from anywhere in the repository.

@mhaessig 
Your change (at version 8aee7a3be34718b3389a366fb4ddb72d6ea69612) is now ready to be sponsored by a Committer.

-------------

PR Comment: https://git.openjdk.org/jdk/pull/24828#issuecomment-2826797122