Bug#1075380: petsc: ftbfs with GCC-14

[Drew Parsons]

Source: petsc
Version: 3.20.6+dfsg1-1
Followup-For: Bug #1075380

petsc still fails this way with scotch 7.0.5 (which has fixed scotch's
own gcc-14 problem).

The issue is that petsc is configured to use default scotch (integer
not specified, meaning int).  But the petsc64 build gets PetscInt
defined as long int.  gcc-14 no longer treats pointers to int and to
long as compatible.

Incidently the (previously tolerated) incompatibility could possible
explain various random 64-bit integer failures (e.g. bug#968118 in dolfin64)

Evidently we need to start configuring 64-bit petsc explicitly against
64-bit scotch (given that petsc is using long, we'd likely want scotch
long rather than int64).