This was discussed in #16597. It makes sense for most of the functions
in this file to be marked inline: many are simple helper functions so
inlining is likely a strict win, and having the return values be
comptime-known may improve userspace code in some cases by preventing it
from unintentionally checking properties of the target at runtime.

This changeset is somewhat conservative: the functions marked inline are
generally returning booleans or simple integers, and many are simple
one-line checks.