Ensure O_NONBLOCK and O_CLOEXEC are defined in pubsub

Author: lpereira

src/lib/lwan-pubsub.c

@@ -20,6 +20,7 @@
 
 #define _GNU_SOURCE
 #include <errno.h>
+#include <fcntl.h>
 #include <pthread.h>
 #include <stdarg.h>
 #include <stdio.h>