x86: unify arch/x86/lib/Makefile(s)

Trivial unification of Makefiles for the
x86 specific library part.
Linking order is slightly modified but should be harmless.

Tested doing a defconfig build before and after and saw
no build changes.

It adds almost as many lines as it deletes - bacause
I broke a few lines up fo readability in the Makefile.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>