MDEV-14174 crash on start with innodb-track-changed-pages

The XtraDB option innodb_track_changed_pages causes
the function log_group_read_log_seg() to be invoked
even when recv_sys==NULL, leading to the SIGSEGV.

This regression was caused by
MDEV-11027 InnoDB log recovery is too noisy

mysql-test/suite/innodb/t/innodb-master.opt

@@ -2,3 +2,4 @@
 --default-storage-engine=MyISAM
 --innodb-strict-mode=0
 --innodb-file-per-table=0
+--loose-innodb-track-changed-pages

storage/xtradb/log/log0log.c

@@ -2503,7 +2503,6 @@ log_group_read_log_seg(
 	ulint	len;
 	ulint	source_offset;
 	ibool	sync;
-	ib_time_t	time;
 
 	ut_ad(mutex_own(&(log_sys->mutex)));
 
@@ -2540,13 +2539,16 @@ log_group_read_log_seg(
 	start_lsn += len;
 	buf += len;
 
-	time = ut_time();
+	if (recv_sys) {
+		ib_time_t time = ut_time();
 
-	if (recv_sys->progress_time - time >= 15) {
-		recv_sys->progress_time = time;
-		ut_print_timestamp(stderr);
-		fprintf(stderr, "  InnoDB: Read redo log up to LSN=%llu\n",
-			start_lsn);
+		if (recv_sys->progress_time - time >= 15) {
+			recv_sys->progress_time = time;
+			ut_print_timestamp(stderr);
+			fprintf(stderr,
+				"  InnoDB: Read redo log up to LSN=%llu\n",
+				start_lsn);
+		}
 	}
 
 	if (start_lsn != end_lsn) {