[PATCH] Fix "value computed is not used" compile warnings with gcc-4.1

Fix gcc4.1 compile warnings "value computed is not used" with
set_current_state() and set_task_state() on i386/SMP and x86-64.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h
index 36a92ed..399145a 100644
--- a/include/asm-i386/system.h
+++ b/include/asm-i386/system.h
@@ -507,7 +507,7 @@
 #define smp_rmb()	rmb()
 #define smp_wmb()	wmb()
 #define smp_read_barrier_depends()	read_barrier_depends()
-#define set_mb(var, value) do { xchg(&var, value); } while (0)
+#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
 #else
 #define smp_mb()	barrier()
 #define smp_rmb()	barrier()