Preperatory patch to simplify the sharing of Makefiles in
arch/x86.

Linus came up with this during a discussion about the ugliness of
ifeq($CONFIG_X86_32),y) and obj-$(CONFIG_X86_32) in the shared
Makefiles.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>