#1241 issue fixing

Due type cast firmware file size compared not with signed int max value. Instead unsigned int max value used and after type casting converted to -1. Then function returns error message.
Type fixed, function working.

src/common.c

@@ -27,6 +27,10 @@
 #define O_BINARY 0
 #endif
 
+#ifndef OFF_T_MAX
+#define OFF_T_MAX 1073741824 // signed long int max value
+#endif
+
 #ifdef _MSC_VER
 #define __attribute__(x)
 #endif
@@ -2200,7 +2204,7 @@ static int map_file(mapped_file_t *mf, const char *path) {
 
   if (sizeof(st.st_size) != sizeof(size_t)) {
     // on 32 bit systems, check if there is an overflow
-    if (st.st_size > (off_t)SSIZE_MAX) {
+	if (st.st_size > (off_t)OFF_T_MAX) {
       fprintf(stderr, "mmap() size_t overflow for file %s\n", path);
       goto on_error;
     }