[PATCH] x86_64: Allow compilation on a 32bit biarch toolchain

This might help on distributions that use a 32bit biarch compiler.

First pass -m64 by default.

Secondly add some more .code32s because at least the Ubuntu biarch
32bit as called by gcc doesn't seem to handle -m64 -m32 as generated
by the Makefile without such assistance.

And finally make sure the linker script can be preprocessed
with a 32bit cpp.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>