Use gmake for BSD systems

This is the same PR as stdpp!559 (merged). The make-package script now checks whether the system is a BSD and if so uses gmake (GNU Make) instead of make to build the package since the latter is incompatible with the GNU Makefiles generated by Coq.

mentioned in merge request stdpp!559 (merged)

Thanks, looks good!

Feel free to add the changelog entry as well. :)

added 134 commits

• a46aaf41...b37d1960 - 132 commits from branch iris:master
• 080198e9 - Use gmake for BSD systems
• 3d5cf36b - Add CHANGELOG.

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I took the liberty of rebasing and adding a CHANGELOG.

Feel free to merge @jung

resolved all threads

added 1 commit

• 29b0fcd9 - changelog: give credit

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enabled an automatic merge when all merge checks for 29b0fcd9 pass

mentioned in commit 69d2820f

merged