Like 90% of the modctl icp architecture can probably go

[nabijaczleweli]

Came across it when doing a const-enforcement pass – modctl.h lists a modctl syscall, approximately 17 different module classes, &c. This looks like a straight import from Illumos – neither linux nor freebsd has one. Nor do they have multiple versions of the solaris module loading framework.

This is currently best-effort shimmed out in modconf.c, but it can probably be a tenth of the line count, and much simpler, if we were to rip out the, like, two layers of indirection.

Noting this down to reference in the aforementioned PR and for the future if I need to burn two quality hours.