tweak inlining

tweak inlining

I used -Winline (optimizing, gcc 11 or 12) to gather warnings
about cases that were considered too expensive for inlining.
Some of these probably used not to happen when we were dropping
assertions during preprocessing in -DNDEBUG builds.
This commit mainly improves size of the compiled binary by several KiB.

- queue_head_impl(): optionally (un)inline; not big but in warnings
- queue_pop_impl(): uninline; too complex for my today's eyes
- kr_rand_bytes(): optionally (un)inline
  The inlining potential there comes from calling with a constant.
- kr_straddr(): uninline.  It's never been meant for hot code,
  and this gives us large savings due to deduplicating the static array.
- For some I couldn't see a good resolution due to restrictions in C.

C hint: `static inline` is probably well known;
the other inline combination is well explained at:
https://stackoverflow.com/a/6312813/587396