Fixed struct timeval undeclared on Windows

examples/streamer/helpers.cpp

@@ -21,7 +21,8 @@
 
 #ifdef _WIN32
 // taken from https://stackoverflow.com/questions/10905892/equivalent-of-gettimeday-for-windows
-#include <Windows.h>
+#include <windows.h>
+#include <winsock2.h> // for struct timeval
 
 struct timezone {
     int tz_minuteswest;