Fix build error with GCC 3.x caused by commit 
b28efd54
"kernel: roundup should only reference arguments once" by constifying
temporary variable used in that macro.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
 #define roundup(x, y) (                                        \
 {                                                      \
-       typeof(y) __y = y;                              \
+       const typeof(y) __y = y;                        \
        (((x) + (__y - 1)) / __y) * __y;                \
 }                                                      \
 )