terminal: set FD_CLOEXEC on pty file descriptors
terminal: set FD_CLOEXEC on pty file descriptors

Signed-off-by: Christian Brauner <48455ab3070520a2d174545c7239d6d0fabd9a83@ubuntu.com>
Cc: Wolfgang Bumiller <bac7898f539fd233d9ce33be7a9eda13ee647930@proxmox.com>

ss1h2a3tw/lxc,hallyn/lxc,caglar10ur/lxc,hallyn/lxc,caglar10ur/lxc,hallyn/lxc,ss1h2a3tw/lxc,caglar10ur/lxc,ss1h2a3tw/lxc