Do not geocode while merging, rely on existing values

This is a performance fix when merging - on a batch merge job it can be kinda crazy & we already have
geocode data for the contacts

CRM/Dedupe/Merger.php

@@ -1191,7 +1191,11 @@ public static function getRowsElementsAndInfo($mainId, $otherId, $checkPermissio
             $locations[$moniker][$blockName][$cnt] = $value;
             // Fix address display
             if ($blockName == 'address') {
+              // For performance avoid geocoding while merging https://issues.civicrm.org/jira/browse/CRM-21786
+              // we can expect existing geocode values to be retained.
+              $value['skip_geocode'] = TRUE;
               CRM_Core_BAO_Address::fixAddress($value);
+              unset($value['skip_geocode']);
               $locations[$moniker][$blockName][$cnt]['display'] = CRM_Utils_Address::format($value);
             }
             // Fix email display