SVS: update isThisType to reject files with a single IFD

See IDR/idr-metadata#699

components/formats-gpl/src/loci/formats/in/SVSReader.java

@@ -174,7 +174,9 @@ else if (description instanceof String) {
           }
           if (imageDescription != null
               && imageDescription.startsWith(APERIO_IMAGE_DESCRIPTION_PREFIX)) {
-            return true;
+            // reject anything with just one IFD, as that indicates there is
+            // no pyramid, thumbnail, label, or macro
+            return tiffParser.getIFDOffsets().length > 1;
           }
         }
         return false;