[git commit nptl] byteswap: unify common definitions

[Mike Frysinger]

commit: http://git.uclibc.org/uClibc/commit/?id=e77fe036cfbcb690d4b2f19d58665bb28d00e4a0
branch: http://git.uclibc.org/uClibc/commit/?id=refs/heads/nptl

The majority of the byteswap functions are the same across all arches, so
setup a common header to provide definitions if they don't exist.  This
allows arches to override only the ones they actually want to implement
with inline assembly.

Signed-off-by: Mike Frysinger <vapier at gentoo.org>
Signed-off-by: Austin Foxley <austinf at cetoncorp.com>

Patch is too large, so refusing to show it