Caprevoke packages

[nwf-msr]

After much delay and yak shaving, here is a first attempt at adding packages for

• snmalloc shims, both upstream (which {c,sh}ould probably go upstream to FreeBSD?) and with extensions for mrs
• a jemalloc-for-mrs shim
• mrs shims configured as per CHERIvoke, Cornucopia, Cornucopia-successor (load barriers), and Cornucopia-successor-but-with-statistics.

I'll get instructions for how to pull the right kernels and then to use these up in the cheribsd wiki. In the interim, it'd be really good to have several more competent people look these over as I definitely felt like I was cutting against the grain writing these (I guess master/subordinate packages are not exactly the common case, though).

[nwf-msr]

Generally looks good.

Huzzah.

I'd be somewhat tempted to make the various mrs-* port into flavors using the FLAVOR mechanism. jemalloc-mrs somewhat complicates this idea.

Maybe it's worth having jemalloc-mrs stand alone and not depend on mrs. I'll take a stab at FLAVORing.

All the ports might benefit from pkg-message files that provide LD_PRELOAD examples.

Can do.

[nwf]

Thanks for the suggestions. FLAVORS turned out to be much less of a pain than I'd feared, I think.

[nwf]

Hold fire; testing has revealed some small bugs (as should be expected).

[nwf-msr]

Things look better now; SWIM want to give this another once-over or try following the instructions, such as they are, at https://github.com/CTSRD-CHERI/cheripedia/wiki/HOWTO:-Use-Cornucopia-with-the-22.12-CheriBSD-Release ?

[kwitaszczyk]

Should these ports only be available for aarch64c? Or would they work for aarch64, riscv64c, riscv64 as well?

[kwitaszczyk]

The ports also must be added to devel/Makefile to be built with poudriere-bulk.