stepcompress: Fix compress_bisect_add() infinite loop

At high step speeds, it is possible to exit the inner scan due to
integer truncation.  Always update minadd or maxadd so that the outer
loop always terminates.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/stepcompress.c

@@ -174,11 +174,15 @@ compress_bisect_add(struct stepcompress *sc)
 
         // Check if a greater or lesser add could extend the sequence
         int32_t maxreach = add*addfactor + maxinterval*(count+1);
-        if (maxreach < point.minp)
+        if (maxreach < point.minp) {
+            minadd = add;
             origmaxinterval = maxinterval;
-        else
+        } else {
+            maxadd = add;
             origmininterval = mininterval;
+        }
 
+        // See if next point would further limit the add range
         if ((minadd+1)*addfactor + origmaxinterval*(count+1) < point.minp)
             minadd = idiv_up(point.minp - origmaxinterval*(count+1)
                              , addfactor) - 1;