Don't disable tcache for lazy-lock.

Don't disable tcache when lazy-lock is configured.  There already exists
a mechanism to disable tcache, but doing so automatically due to
lazy-lock causes surprising performance behavior.

include/jemalloc/internal/tcache.h

@@ -188,8 +188,6 @@ tcache_get(tsd_t *tsd, bool create)
 
 	if (!config_tcache)
 		return (NULL);
-	if (config_lazy_lock && !isthreaded)
-		return (NULL);
 
 	tcache = tsd_tcache_get(tsd);
 	if (!create)