Garbage collect the bswap routines from libstand. The declaration was
wrapped in an i386 ifdef with a comment questioning their usefulness even
there. It turns out they aren't referenced anywhere, but their presence
prevents using sys/endian.h in libstand code.

These days, sys/endian.h provides much better support for such things, using
compiler builtins and inline functions (and creating connections between
libstand code and header files from sys/ would not be breaking new ground).