MDEV-38507: Reduce fadvise() overhead on pipes in Mariabackup#4748

grooverdan merged 2 commits intoMariaDB:10.11MariaDB/server:10.11from

kjarir:MDEV-38507-mariabackup-overheadkjarir/server:MDEV-38507-mariabackup-overheadCopy head branch name to clipboard