We now depend on explicitly creating memory arenas and disabling tcache
on those, and these features are not available with jemalloc < 4.
Instead of working around these issues, make the jemalloc >= 4.0.0 hard
requirement by looking for sdallocx() symbol that's only available from
that version.
The jemalloc < 4 was only used by RHEL 7 which is not supported since
BIND 9.19+.
d862f4bc64