Hmm, most of the other packages (dpkg, etc) invert that arch list, so instead of this:
libselinux1-dev (>= 1.28-4) [alpha amd64 arm armeb armel hppa i386 ia64 m68k mips mipsel powerpc powerpcspe ppc64 s390 sh4 sparc]
They have this:
libselinux1-dev (>= 1.28-4) [!hurd-i386 !kfreebsd-i386 !kfreebsd-amd64]
Admittedly long-term if Debian ends up supporting many non-linux platforms dpkg may need to support a better syntax, but for now mimicing dpkg WRT the selinux build-dep is probably the right way to go.
Cheers,
Kyle Moffett