INT16_MAX is a better end of array marker than -1

DCCEXParser.cpp

@@ -47,7 +47,7 @@
 #define SENDFLASHLIST(stream,flashList)                 \
     for (int16_t i=0;;i+=sizeof(flashList[0])) {                            \
         int16_t value=GETHIGHFLASHW(flashList,i);       \
-        if (value<0) break;                            \
+        if (value==INT16_MAX) break;                            \
         StringFormatter::send(stream,F(" %d"),value);   \
     }