setup_once.h cleanup and sync

src/setup.h

@@ -226,4 +226,27 @@ int fileno( FILE *stream);
 #include "setup_once.h"
 #endif
 
+/*
+ * Definition of our NOP statement Object-like macro
+ */
+
+#ifndef Curl_nop_stmt
+#  define Curl_nop_stmt do { } WHILE_FALSE
+#endif
+
+/*
+ * Ensure that Winsock and lwIP TCP/IP stacks are not mixed.
+ */
+
+#if defined(__LWIP_OPT_H__)
+#  if defined(SOCKET) || \
+     defined(USE_WINSOCK) || \
+     defined(HAVE_ERRNO_H) || \
+     defined(HAVE_WINSOCK_H) || \
+     defined(HAVE_WINSOCK2_H) || \
+     defined(HAVE_WS2TCPIP_H)
+#    error "Winsock and lwIP TCP/IP stack definitions shall not coexist!"
+#  endif
+#endif
+
 #endif /* HEADER_CURL_SRC_SETUP_H */