Log the correct ending timestamp in recovery_target_xid mode.

When ending recovery based on recovery_target_xid matching with
recovery_target_inclusive = off, we printed an incorrect timestamp
(always 2000-01-01) in the "recovery stopping before ... transaction"
log message.  This is a consequence of sloppy refactoring in
c945af80c: the code to fetch recordXtime out of the commit/abort
record used to be executed unconditionally, but it was changed
to get called only in the RECOVERY_TARGET_TIME case.  We need only
flip the order of operations to restore the intended behavior.

Per report from Torsten Förtsch.  Back-patch to all supported
branches.

Discussion: https://postgr.es/m/CAKkG4_kUevPqbmyOfLajx7opAQk6Cvwkvx0HRcFjSPfRPTXanA@mail.gmail.com

src/backend/access/transam/xlog.c

@@ -5914,8 +5914,13 @@ recoveryStopsBefore(XLogReaderState *record)
 		stopsHere = (recordXid == recoveryTargetXid);
 	}
 
-	if (recoveryTarget == RECOVERY_TARGET_TIME &&
-		getRecordTimestamp(record, &recordXtime))
+	/*
+	 * Note: we must fetch recordXtime regardless of recoveryTarget setting.
+	 * We don't expect getRecordTimestamp ever to fail, since we already know
+	 * this is a commit or abort record; but test its result anyway.
+	 */
+	if (getRecordTimestamp(record, &recordXtime) &&
+		recoveryTarget == RECOVERY_TARGET_TIME)
 	{
 		/*
 		 * There can be many transactions that share the same commit time, so