Fix compatibility with BSD tar by supporting both tar and gtar

[Sonu0305]

This PR addresses the issue (#1315) with packaging and tarball creation on systems using BSD tar. On such systems, the default tar command may not work as expected, and GNU tar (gtar) is required instead.

[Sonu0305]

Hi @cbm755 ,
I kindly request if you could review the pull request. Please let me know if any further changes or adjustments are needed.
Thank you for your time and support!

[cbm755]

Looks good to me! This seems familiar, maybe something that has come up in other Octave packages... If you have a moment, can you also check https://github.com/gnu-octave/octave-doctest? maybe image and interval too? IIRC, the Makefile was pretty common...

[Sonu0305]

Looks good to me! This seems familiar, maybe something that has come up in other Octave packages... If you have a moment, can you also check https://github.com/gnu-octave/octave-doctest? maybe image and interval too? IIRC, the Makefile was pretty common...

@cbm755
For octave-doctest:
The Makefile for doctest also sets up support for tar, but in a slightly different way. It attempts to find gtar (GNU tar) first and, if not found, defaults to using the system tar. This is done through the line:

TAR := $(shell which gtar 2>/dev/null || echo tar)

Do you want me to modify the doctest Makefile to use the same method as in symbolic's Makefile, where the TAR variable is not prioritized (just uses whatever tar is available in the environment)?