[PATCH] i386: fix rwsem build bug on CONFIG_M386=y

CONFIG_M386 turns on spinlock-based generic rwsems - which surprises the
semaphore.S rwsem stubs. Tested both with and without CONFIG_M386.

Reported-by: Klaus Knopper <knopper@knopper.net>
Triaged-by: Adrian Bunk <bunk@stusta.de>

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andi Kleen <ak@suse.de>