Remove struct proc p_sched and struct thread td_sched.

[kib]

Summary

p_sched is unused.

td_sched is pointless, the corresponding memory is always next after the struct thread itself, except for thread0. The later is easily fixable, it only looks ugly. IMO it is better to remove the useless indirection.

[kib]

Add pure2 attribute.

[jhb]

sys/kern/sched_ule.c

1628 ↗

(On Diff #17283)

Maybe use a 'struct td_sched *ts' helper var here so it's more readable?

sys/sys/proc.h

886 ↗

(On Diff #17283)

Perhaps move this up to just below 'struct thread' definition so all the types are together?

[kib]

Move the struct thread0_storage right after the struct thread.
For several sched_ule.c functions, reduce number of td_get_sched() calls by using local vars.
Reorganize asserts about thread0_storage layout, making it static and correcting the size of the tail (reducing it to correct size).