Import lwIP contrib rep

... from http://git.savannah.gnu.org/cgit/lwip/lwip-contrib.git/ into contrib/ subdir, STABLE-2_1_0_RELEASE tag
lwIP contrib is now officially frozen
TODO: Fix build

contrib/ports/win32/check/config.h

@@ -0,0 +1,30 @@
+/* config.h for check-0.11.0 on win32 under MSVC/MinGW */
+
+#ifdef _MSC_VER
+
+typedef unsigned int pid_t;
+typedef unsigned int uint32_t;
+
+typedef int ssize_t;
+#define snprintf _snprintf
+
+#define HAVE_DECL_STRDUP 1
+#define HAVE_DECL_FILENO 1
+#define HAVE_DECL_PUTENV 1
+
+#define _CRT_SECURE_NO_WARNINGS
+
+/* disable some warnings */
+#pragma warning (disable: 4090) /* const assigned to non-const */
+#pragma warning (disable: 4996) /* fileno is deprecated */
+
+#endif /* _ MSC_VER */
+
+
+#define LWIP_UNITTESTS_NOFORK
+
+#include <io.h>
+
+typedef unsigned int clockid_t;
+typedef unsigned int timer_t;
+#define STRUCT_TIMESPEC_DEFINITION_MISSING