[PATCH] Add support for OpenMP fortran user defined reductions

[FX]

> As discussed with Tobias on IRC yesterday, the fact that I'd like to
> eventually backport the Fortran OpenMP 4.0 support to 4.9 branch
> poses a problem with the module.c changes

But this is by design, because we’re not supposed to add new features (especially API-changing or module-changing ones) in a release branch. The compatibility fixes you propose will increase the complexity of the module reader code, and creates some precedent.

I don’t think there’s much pressure from the “general public” for Fortran OpenMP 4.0, so having it in 4.10 only rather than 4.9 is probably not such a big deal.

FX