Bug#1074988: gerris: ftbfs with GCC-14

[Drew Parsons]

Source: gerris
Followup-For: Bug #1074988

Gerris upstream has not been updated since 2013.
We probably won't be able to (easily) patch it to work with gcc-14.

Probably we should just drop the gerris package from Debian.

Upstream has moved on to basilisk, which supersedes gerris.

  http://basilisk.fr/

Those who need the functionality of gerris should put in the work to
package basilisk. The packaging requirements are probably much the
same as gerris.

For my own applications solving differential equations, I've been
using FEniCS (fenicsx) for finite element computations.

Drew