fix type error in pthread_create, introduced with pthread_getattr_np

src/thread/pthread_create.c

@@ -123,7 +123,7 @@ int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp
 		size_t need = libc.tls_size + __pthread_tsd_size;
 		size = attr._a_stacksize + DEFAULT_STACK_SIZE;
 		stack = (void *)(attr._a_stackaddr & -16);
-		stack_limit = attr._a_stackaddr - size;
+		stack_limit = (void *)(attr._a_stackaddr - size);
 		/* Use application-provided stack for TLS only when
 		 * it does not take more than ~12% or 2k of the
 		 * application's stack space. */