Add DESTDIR support for python2/python3

[embray]

Implements #24024 for python2 and python3.

Depends on #24599
Depends on #25039
Depends on #23733

Component: build

Keywords: destdir python2 python3

Author: Erik Bray

Branch/Commit: eca6471

Reviewer: Julian Rüth

Issue created by migration from https://trac.sagemath.org/ticket/25043

[embray]

comment:2

(already merges without conflict with #23733)

[embray]

Changed dependencies from #24599, #25039 to #24599, #25039, #23733

[sagetrac-git]

Changed commit from 2c0b902 to eca6471

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

18c8d3b	update python2/python3 to use sage-dist-helpers and support DESTDIR install
eca6471	update package versions for buildbot

[saraedum]

comment:5

feel free to set this to positive review if you have verified that it actually works.

[saraedum]

Reviewer: Julian Rüth