Add RTX-RTOS support

src/arch_rtx_lwip.h

@@ -0,0 +1,40 @@
+#pragma once
+
+#if MG_ARCH == MG_ARCH_RTX_LWIP
+
+#include <ctype.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+#if defined(__GNUC__)
+#include <sys/stat.h>
+#include <sys/time.h>
+#else
+struct timeval {
+  time_t tv_sec;
+  long tv_usec;
+};
+#endif
+
+#include <lwip/sockets.h>
+
+#if LWIP_SOCKET != 1
+// Sockets support disabled in LWIP by default
+#error Set LWIP_SOCKET variable to 1 (in lwipopts.h)
+#endif
+
+#define mkdir(a, b) (-1)
+
+#ifndef MG_IO_SIZE
+#define MG_IO_SIZE 512
+#endif
+
+#ifndef MG_PATH_MAX
+#define MG_PATH_MAX 128
+#endif
+
+
+#endif