[subset] fix infinite loop bug in looping through tables for subsetting.
diff --git a/src/hb-subset.cc b/src/hb-subset.cc
index 2a2f855..b253817 100644
--- a/src/hb-subset.cc
+++ b/src/hb-subset.cc
@@ -363,8 +363,8 @@
         continue;
       }
       success = success && _subset_table (plan, tag);
-      offset += count;
     }
+    offset += count;
   } while (count == ARRAY_LENGTH (table_tags));
 
   hb_face_t *result = success ? hb_face_reference(plan->dest) : hb_face_get_empty();