Initialize arena_bin_info at compile time rather than at boot time.

This resolves #370.

test/unit/junk.c

@@ -23,7 +23,7 @@ watch_junking(void *p)
 }
 
 static void
-arena_dalloc_junk_small_intercept(void *ptr, arena_bin_info_t *bin_info)
+arena_dalloc_junk_small_intercept(void *ptr, const arena_bin_info_t *bin_info)
 {
 	size_t i;