Add JEMALLOC_ALLOC_JUNK and JEMALLOC_FREE_JUNK macros

Replace hardcoded 0xa5 and 0x5a junk values with JEMALLOC_ALLOC_JUNK and
JEMALLOC_FREE_JUNK macros, respectively.

include/jemalloc/internal/tcache.h

@@ -381,9 +381,10 @@ tcache_alloc_large(tsd_t *tsd, arena_t *arena, tcache_t *tcache, size_t size,
 		}
 		if (likely(!zero)) {
 			if (slow_path && config_fill) {
-				if (unlikely(opt_junk_alloc))
-					memset(ret, 0xa5, usize);
-				else if (unlikely(opt_zero))
+				if (unlikely(opt_junk_alloc)) {
+					memset(ret, JEMALLOC_ALLOC_JUNK,
+					    usize);
+				} else if (unlikely(opt_zero))
 					memset(ret, 0, usize);
 			}
 		} else

include/jemalloc/internal/util.h

@@ -40,6 +40,10 @@
  */
 #define	MALLOC_PRINTF_BUFSIZE	4096
 
+/* Junk fill patterns. */
+#define	JEMALLOC_ALLOC_JUNK	0xa5
+#define	JEMALLOC_FREE_JUNK	0x5a
+
 /*
  * Wrap a cpp argument that contains commas such that it isn't broken up into
  * multiple arguments.