seccomp: open memfd read-write
seccomp: open memfd read-write

Makes it easier to implement syscalls which need to write to
a buffer passed by user space as a pointer.

Signed-off-by: Wolfgang Bumiller <bac7898f539fd233d9ce33be7a9eda13ee647930@proxmox.com>

hallyn/lxc,hallyn/lxc,hallyn/lxc