Use sage-dist-helpers + add DESTDIR support for flint and arb

[embray]

This is implementing #24024 for the flint and arb packages which use basically the same "build system".

This shouldn't change much anything in the end result of installing these packages, but I bumped the version numbers just to ensure testing on the buildbots.

Depends on #23733

Component: build

Keywords: destdir flint arb

Author: Erik Bray

Branch/Commit: a9971d7

Reviewer: Frédéric Chapoton

Issue created by migration from https://trac.sagemath.org/ticket/25035

[embray]

comment:2

Two of the failing patchbots seem to be...really broken, and in different ways. I don't think it has anything directly to do with this ticket...

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

b4ecda9	trac 23733: deprecate SAGE64 and CFLAG64
905e4d4	Stop supporting SAGE64 except in Numpy
eecf581	Merge branch 'u/jdemeyer/no-sage64' into u/embray/build/destdir-arb-flint

[sagetrac-git]

Changed commit from f63449a to eecf581

[embray]

Dependencies: #23733

[embray]

New commits:

b4ecda9	trac 23733: deprecate SAGE64 and CFLAG64
905e4d4	Stop supporting SAGE64 except in Numpy
eecf581	Merge branch 'u/jdemeyer/no-sage64' into u/embray/build/destdir-arb-flint

[saraedum]

Work Issues: merge conflicts