Use the new x86 setup code for x86-64; unify with i386

This unifies arch/*/boot (except arch/*/boot/compressed) between
i386 and x86-64, and uses the new x86 setup code for x86-64 as well.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --cc arch/x86_64/boot/Makefile
Simple merge

diff --cc arch/x86_64/boot/bootsect.S
Simple merge

diff --cc arch/x86_64/boot/compressed/Makefile
Simple merge

diff --cc arch/x86_64/boot/install.sh
Simple merge

diff --cc arch/x86_64/boot/mtools.conf.in
Simple merge

diff --cc arch/x86_64/boot/setup.S
Simple merge

diff --cc arch/x86_64/boot/tools/build.c
Simple merge