fix: count only the hash changes an export writes

RomM kept hashes the truth contradicts beside the corrected one, RetroDECK kept a cleared md5, Recalbox counted changes on an element it writes back whole, and two record formats counted fills no record could hold.

scripts/exporter/systemdat_exporter.py

@@ -134,6 +134,9 @@ class Exporter(BaseExporter):
         )
         return lines
 
+    def fills(self, fe: NativeFile, field_name: str) -> bool:
+        return self.states(fe, field_name) and self.record_fills(fe, field_name)
+
     def render(
         self,
         systems: dict[str, NativeSystem],