Add DESTDIR support for pari

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Implements #24024 for pari.

Component: **build**

Keywords: **destdir pari**

Author: **Erik Bray**

Branch/Commit: **[`9a46a21`](https://github.com/sagemath/sagetrac-mirror/commit/9a46a2166840b13bf8ec9e92f2229ef9266b85a9)**

Reviewer: **Julian Rüth, Jeroen Demeyer**

_Issue created by migration from https://trac.sagemath.org/ticket/25143_

