for #320, refine code.

@@ -1129,10 +1129,10 @@ void SrsRtmpConn::change_mw_sleep(int sleep_ms)
 
 void SrsRtmpConn::play_set_sock_options()
 {
-    int fd = st_netfd_fileno(stfd);
-    
 #ifdef SRS_PERF_TCP_NODELAY
     if (true) {
+        int fd = st_netfd_fileno(stfd);
+    
         socklen_t nb_v = sizeof(int);
         
         int ov = 0;

@@ -88,6 +88,8 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 // generated by configure.
 #include <srs_auto_headers.hpp>
+// important performance options.
+#include <srs_core_performance.hpp>
 
 // free the p and set to NULL.
 // p must be a T*.