repmgrd: catch cases where more than one node has initiated voting

The node(s) with higher ID will "yield", leaving the decision making
up to the node with the lower ID.

This happens very rarely, usually when the random delay is close
enough on two or mode nodes that vote initiation is simultaneous.

repmgr.c

@@ -206,13 +206,11 @@ request_vote(PG_FUNCTION_ARGS)
 
 	initStringInfo(&query);
 
-#if (PG_VERSION_NUM >= 100000)
 	appendStringInfo(
 		&query,
+#if (PG_VERSION_NUM >= 100000)
 		"SELECT pg_catalog.pg_last_wal_receive_lsn()");
 #else
-	appendStringInfo(
-		&query,
 		"SELECT pg_catalog.pg_last_xlog_receive_location()");
 #endif