Add btrfs support
Fix MK_ARRAY()

# gpg: Signature made Thu 03 Sep 2020 00:26:37 BST
# gpg:                using RSA key CD2F75DDC8E3A4DC2E4F5173F30C38BD3F2FBE3C
# gpg:                issuer "laurent@vivier.eu"
# gpg: Good signature from "Laurent Vivier <lvivier@redhat.com>" [full]
# gpg:                 aka "Laurent Vivier <laurent@vivier.eu>" [full]
# gpg:                 aka "Laurent Vivier (Red Hat) <lvivier@redhat.com>" [full]
# Primary key fingerprint: CD2F 75DD C8E3 A4DC 2E4F  5173 F30C 38BD 3F2F BE3C

* remotes/vivier2/tags/linux-user-for-5.2-pull-request:
  linux-user: Add support for btrfs ioctls used to scrub a filesystem
  linux-user: Add support for btrfs ioctls used to manage quota
  linux-user: Add support for two btrfs ioctls used for subvolume
  linux-user: Add support for a group of btrfs inode ioctls
  linux-user: Add support for btrfs ioctls used to get/set features
  linux-user: Add support for btrfs ioctls used to manipulate with devices
  linux-user: Add support for a group of btrfs ioctls used for snapshots
  linux-user: Add support for a group of btrfs ioctls used for subvolumes
  linux-user: fix implicit conversion from enumeration type error

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>