src: add fcntl.h include to node.cc

nodejs#11863 adds _O_RDWR to node.cc
which is defined in fcntl.h. This adds this include directly to
node.cc.

Author: bzoz

src/node.cc

@@ -80,6 +80,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
+#include <fcntl.h>
 
 #include <string>
 #include <vector>