Move reentrancy_level to the beginning of TSD.

src/arena.c

@@ -1958,7 +1958,7 @@ arena_new(tsdn_t *tsdn, unsigned ind, extent_hooks_t *extent_hooks) {
 		 * If we're here, then arena 0 already exists, so bootstrapping
 		 * is done enough that we should have tsd.
 		 */
-		int *reentrancy_level = tsd_reentrancy_levelp_get(tsdn_tsd(
+		int8_t *reentrancy_level = tsd_reentrancy_levelp_get(tsdn_tsd(
 		    tsdn));
 		++*reentrancy_level;
 		hooks_arena_new_hook();

src/jemalloc.c

@@ -1662,7 +1662,7 @@ imalloc_body(static_opts_t *sopts, dynamic_opts_t *dopts) {
 	 * bother getting the old level, so we shouldn't try to reset it.  This
 	 * is indicated by leaving the pointer as NULL.
 	 */
-	int *reentrancy_level = NULL;
+	int8_t *reentrancy_level = NULL;
 
 	/* Initialize (if we can't prove we don't have to). */
 	if (sopts->slow) {