PATCH: Use x86-64 bits/byteswap.h for both i386 and x86_64

[Roland McGrath]

I'd prefer to see this split up even smaller.

byteswap-16.h isn't changing, so you can do that move alone in one change.

Send another change making x86_64/bits/byteswap.h i386-compatible.

Then send another change just moving x86{_64,}/bits/byteswap.h without
changing the contents at all.

For all these things, I think that they should be done this way: first, a
separate change that makes the x86_64 file fully compatible with i386;
second, a change that just does the move and nothing else.  For the pure
file-moving changes, you can use git diff -M so that it's easy to see
that it's a verbatim move.


Thanks,
Roland