The current Octave support is utterly broken (both in stable and unstable), it
crashes Octave. It relies on an unofficial Octave app for
macOS (https://octave-app.org), which is infrequently updated.
This commits drop support for Octave in the macOS package. We will now tell our
macOS+octave users to use the Homebrew Dynare package (which is maintained by
the Homebrew team, and is in reasonably good shape).
Add -std=legacy to FFLAGS.
Do the same for the Windows package, even though we don’t yet use version 10 of
gfortran (but that will of course happen at some point).
* The macOS snapshot until this point did not work unless the user had already installed `libmatio`, `gsl`, and `gcc` via Homebrew.
* We are not modifying `m4/ax_matio.m4` as we want to still be able to compile against shared libraries in development
Sébastien Villemot
Houtan Bastani