Fix hasher resolution for long windows.

PiperOrigin-RevId: 651781560
diff --git a/c/enc/quality.h b/c/enc/quality.h
index 4fe649e..1065f23 100644
--- a/c/enc/quality.h
+++ b/c/enc/quality.h
@@ -194,14 +194,14 @@
        hasher already works well with large window. So the changes are:
        H3 --> H35: for quality 3.
        H54 --> H55: for quality 4 with size hint > 1MB
-       H6 --> H65: for qualities 5, 6, 7, 8, 9. */
+       H6/H68 --> H65: for qualities 5, 6, 7, 8, 9. */
     if (hparams->type == 3) {
       hparams->type = 35;
     }
     if (hparams->type == 54) {
       hparams->type = 55;
     }
-    if (hparams->type == 6) {
+    if (hparams->type == 6 || hparams->type == 68) {
       hparams->type = 65;
     }
   }