Almost all uses, if not all of them, are wrong, according to the
semantics of BUILD_DEPENDS (packages built for target available for
use _by_ tools at build-time) and TOOL_DEPEPNDS (packages built for
host available for use _as_ tools at build-time).
No change to BUILD_DEPENDS as used correctly inside buildlink3.
As proposed on tech-pkg:
https://mail-index.netbsd.org/tech-pkg/2023/06/03/msg027632.html
This is the logic we have in gcc8. Replicate it to newer GCC packages.
Using pkgsrc zlib causes problems linking gcov(1) on at least Linux
and SunOS. It is not worth bend-over-backwards rpath-patching.
