Consolidate ARRAY_SIZE macro; remove one unneeded global var (walter harms <wharms@bfs.de>)

diff --git a/coreutils/od_bloaty.c b/coreutils/od_bloaty.c
index 3250856..af5eba9 100644
--- a/coreutils/od_bloaty.c
+++ b/coreutils/od_bloaty.c
@@ -158,7 +158,7 @@
    initializer in the width_bytes array.  */
 struct dummy {
 	int assert_width_bytes_matches_size_spec_decl
-		[sizeof width_bytes / sizeof width_bytes[0] == N_SIZE_SPECS ? 1 : -1];
+		[ARRAY_SIZE(width_bytes) == N_SIZE_SPECS ? 1 : -1];
 };
 
 static size_t string_min;