Core: read/write locks are also required by the Stream module.

Signed-off-by: Piotr Sikora <piotrsikora@google.com>

src/core/ngx_rwlock.c

diff --git a/src/core/ngx_rwlock.c b/src/core/ngx_rwlock.c
index 1404c6e..905de78 100644
--- a/src/core/ngx_rwlock.c
+++ b/src/core/ngx_rwlock.c
@@ -111,7 +111,7 @@
 
 #else
 
-#if (NGX_HTTP_UPSTREAM_ZONE)
+#if (NGX_HTTP_UPSTREAM_ZONE || NGX_STREAM_UPSTREAM_ZONE)
 
 #error ngx_atomic_cmp_set() is not defined!