[PATCH] sparc32: add atomic_sub_and_test()

Add atomic_sub_and_test() to sparc32, implemented in terms of
atomic_sub_return(), so reiser4 can be simultaneously microoptimized for
x86 and made to pass compilation testing on sparc32.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/asm-sparc/atomic.h

@@ -46,6 +46,7 @@ extern void atomic_set(atomic_t *, int);
 #define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
 
 #define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
+#define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)
 
 /* This is the old 24-bit implementation.  It's still used internally
  * by some sparc-specific code, notably the semaphore implementation.