Patch from Nicolas Pitre

Since:

	if (unlikely(__res || __ex_flag))

produces worse code on ARM than:

	if (unlikely(__res | __ex_flag))

I therefore made it more explicit:

	__res |= __ex_flag;
	if (unlikely(__res != 0))

so it is not seen as a typo again.

Also made everything static inline rather than macros for better readability
(both produce the same code after all).

And finally added missing \t from multi-line assembly code.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

add the ARM version of mutex.h, which is optimized in assembly for
ARMv6, and uses the xchg implementation on pre-ARMv6.

Signed-off-by: Ingo Molnar <mingo@elte.hu>