fix st_archive issue

Author: jedwards4b

cime_config/config_archive.xml

@@ -15,7 +15,7 @@
     <hist_file_extension>ic.[-\d+]+(\._\d*)?\.nc(\.\d*)?$</hist_file_extension>
     <hist_file_ext_regex>\w+\.\w+(\._\d*)?</hist_file_ext_regex>
     <rpointer>
-      <rpointer_file>rpointer.ocn$NINST_STRING</rpointer_file>
+      <rpointer_file>rpointer.ocn$NINST_STRING.$DATENAME</rpointer_file>
       <rpointer_content>$CASE.mom6$NINST_STRING.r.$DATENAME.nc</rpointer_content>
     </rpointer>
   </comp_archive_spec>