40cf6f3659
- Addresses the issue described in PR/38828. - Some simplification in threading and sleepq subsystems. - Eliminates pmap_collect() and, as a side note, allows pmap optimisations. - Eliminates XS_CTL_DATA_ONSTACK in scsipi code. - Avoids few scans on LWP list and thus potentially long holds of proc_lock. - Cuts ~1.5k lines of code. Reduces amd64 kernel size by ~4k. - Removes __SWAP_BROKEN cases. Tested on x86, mips, acorn32 (thanks <mpumford>) and partly tested on acorn26 (thanks to <bjh21>). Discussed on <tech-kern>, reviewed by <ad>.