(partially) Fix Bug#55227 Fix compiler warnings in innodb with gcc 4.6

Fix compiler warning:
log/log0recv.c: In function 'recv_recovery_from_checkpoint_start_func':
log/log0recv.c:2894:14: error: variable 'archived_lsn' set but not used [-Werror=unused-but-set-variable]

storage/innodb_plugin/log/log0recv.c

@@ -2891,7 +2891,9 @@ recv_recovery_from_checkpoint_start_func(
 	ib_uint64_t	old_scanned_lsn;
 	ib_uint64_t	group_scanned_lsn;
 	ib_uint64_t	contiguous_lsn;
+#ifdef UNIV_LOG_ARCHIVE
 	ib_uint64_t	archived_lsn;
+#endif /* UNIV_LOG_ARCHIVE */
 	byte*		buf;
 	byte		log_hdr_buf[LOG_FILE_HDR_SIZE];
 	ulint		err;
@@ -2946,7 +2948,9 @@ recv_recovery_from_checkpoint_start_func(
 
 	checkpoint_lsn = mach_read_ull(buf + LOG_CHECKPOINT_LSN);
 	checkpoint_no = mach_read_ull(buf + LOG_CHECKPOINT_NO);
+#ifdef UNIV_LOG_ARCHIVE
 	archived_lsn = mach_read_ull(buf + LOG_CHECKPOINT_ARCHIVED_LSN);
+#endif /* UNIV_LOG_ARCHIVE */
 
 	/* Read the first log file header to print a note if this is
 	a recovery from a restored InnoDB Hot Backup */