math/octave-forge: broken on armv7

After dependency octave-forge-io is installed, octave detects for
every following forge package that "the octave packaging system is
probably corrupt, so it will be rebuilt." This means that for each
additional forge package, all previous packages are reinstalled,
leading to O(n^2) runtime in post-install and a very long time of up
to 40 hours for the package build to complete.

Mark the package as broken on armv7 until this can be figured out.
No functionality is lost as the individual forge packages can be
installed as desired. Other architectures are not known to be affected.

Reported by: marklmi@yahoo.com
MFH: 2025Q1