tools/git: ensure git-arc is more platform indepdendent

[freebsd_igalic.co]

Summary

Linux systems' tail doesn't have -r.
Instead, we can use git's own --reverse sorting for rev-lists.

[imp]

tools/tools/git/git-arc.sh

367

why not

_commits=$(git rev-list --reverse $_commits)

instead?

[freebsd_igalic.co]

use git's own --reverse sorting for rev-list

[freebsd_igalic.co]

good point.
(mostly because I assumed that the people who wrote this knew git better than I do, and have exhausted its options already)

[ihor_antonovs.family]

It seems that this diff does not apply cleanly on top of main:
Here is why:
patch assumes: _commits=$(git rev-list $_commits | (tail -r 2>/dev/null || tac))
while in reality: _commits=$(git rev-list $_commits | tail -r)

https://reviews.freebsd.org/source/src/browse/main/tools/tools/git/git-arc.sh$343

[freebsd_igalic.co]

fix broken diff

[freebsd_igalic.co]

@ihor_antonovs.family Fixed.