Figure out kldxref on cross builds

[artemist]

FreeBSD will not load module dependencies unless it has a linker.hints file in the modules directory. We can do this during build on native builds, but there seems to be no way to compile the required kldxref tool with compat for cross-builds.

We should figure out how to make a service that runs kldxref on first boot, or decide to not care about cross builds.

[rhelmot]

first boot services are easy with rc - the system keeps a "first boot sentinel" and will automatically only run services tagged firstboot when it is missing, then automatically creates the sentinel.

[artemist]

True, the problem is that we would want to put linker.hints with the kernel modules, which is in the store

[rhelmot]

on one hand! we already have services which cannot build cross, it's "the entire graphical system"

on the other hand! we should really care about cross!

[rhelmot]

maybe just do #12 and suffer

[artemist]

My current solution is to only run kldxref on native builds, and you don't get dependencies on cross builds, not optimal but it's easy.