HANXIN ECI conversion, GB 18030 LIBICONV port; some codeword fixes; optimized encoding modes

backend/reedsol.c

@@ -51,6 +51,8 @@
 #include <stdio.h>		// only needed for debug (main)
 #ifdef _MSC_VER
 #include <malloc.h>
+#else
+#include <stdlib.h>
 #endif
 #include "reedsol.h"
 static int logmod; // 2**symsize - 1