[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: NTakashi Iwai <tiwai@suse.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

include/asm-i386/system.h

@@ -507,7 +507,7 @@ struct alt_instr {
 #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()

include/asm-x86_64/system.h

@@ -327,7 +327,7 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
 #define wmb()	asm volatile("" ::: "memory")
 #endif
 #define read_barrier_depends()	do {} while(0)
-#define set_mb(var, value) do { xchg(&var, value); } while (0)
+#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
 #define set_wmb(var, value) do { var = value; wmb(); } while (0)
 
 #define warn_if_not_ulong(x) do { unsigned long foo; (void) (&(x) == &foo); } while (0)