science/openmc: mark universally BROKEN

clang-19 has propagated from 15 to FreeBSD 13.5 and 14.3, so
only 14.2 might have a chance to compile this, and isn't going
to be maintained much longer. So extend from BROKEN_FreeBSD_15
to BROKEN.

Let's revisit fmt 11 compatibility once the compiler issues has been
sorted out.