Ensure PENDING/ELAPSED use a 32-bit integer

Marlin/src/core/millis_t.h

@@ -25,5 +25,5 @@
 
 typedef uint32_t millis_t;
 
-#define PENDING(NOW,SOON) ((long)(NOW-(SOON))<0)
+#define PENDING(NOW,SOON) ((int32_t)(NOW-(SOON))<0)
 #define ELAPSED(NOW,SOON) (!PENDING(NOW,SOON))