There's really no need for all the complex #ifdefs present and, on top
of that, it didn't even work correctly for all NetBSD architectures.
Simply use endian.h and drop the rest. (Since there is no upstream for
this code anymore, there's no concern about complicating future merges,
either. This change is also consistent with what FreeBSD and OpenBSD
did years ago.)
Addresses PR toolchain/53880 (reported by maya@, originally encountered
by me on macppc when building a package that pulls in nameser_compat.h
before nameser.h by necessity -- necessity, that is, on another OS).
