use REALLOC_ARRAY for changing the allocation size of arrays

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/commit-slab.h b/commit-slab.h
index 375c9c7..f37ec38 100644
--- a/commit-slab.h
+++ b/commit-slab.h
@@ -90,8 +90,7 @@
 									\
 	if (s->slab_count <= nth_slab) {				\
 		int i;							\
-		s->slab = xrealloc(s->slab,				\
-				   (nth_slab + 1) * sizeof(*s->slab));	\
+		REALLOC_ARRAY(s->slab, nth_slab + 1);			\
 		stat_ ##slabname## realloc++;				\
 		for (i = s->slab_count; i <= nth_slab; i++)		\
 			s->slab[i] = NULL;				\