Arena: Loosen arena_may_have_muzzy restrictions.

If there are custom extent hooks, pages_can_purge_lazy is not necessarily the
right guard.  We could check ehooks_are_default too, but the case where
purge_lazy is unsupported is rare and getting rarer.  Just checking the decay
interval captures most of the benefit.

src/arena.c

@@ -420,7 +420,7 @@ arena_large_ralloc_stats_update(tsdn_t *tsdn, arena_t *arena, size_t oldusize,
 
 static bool
 arena_may_have_muzzy(arena_t *arena) {
-	return (pages_can_purge_lazy && (arena_muzzy_decay_ms_get(arena) != 0));
+	return arena_muzzy_decay_ms_get(arena) != 0;
 }
 
 extent_t *