Separate out iomgr-specific constants into a separate header
diff --git a/src/core/lib/iomgr/socket_windows.c b/src/core/lib/iomgr/socket_windows.c
index d7d5f6f..e9d0ced 100644
--- a/src/core/lib/iomgr/socket_windows.c
+++ b/src/core/lib/iomgr/socket_windows.c
@@ -31,7 +31,7 @@
  *
  */
 
-#include <grpc/support/port_platform.h>
+#include "src/core/lib/iomgr/port.h"
 
 #ifdef GPR_WINSOCK_SOCKET