btrfs: provide fallback definitions for BTRFS_IOC_QUOTA_RESCAN*

btrfs: provide fallback definitions for BTRFS_IOC_QUOTA_RESCAN*

<linux/btrfs.h> was introduced in linux v3.9-rc1 while some
of btrfs ioctls were added later, e.g. BTRFS_IOC_QUOTA_RESCAN
and BTRFS_IOC_QUOTA_RESCAN_STATUS in v3.10-rc2,
or BTRFS_IOC_QUOTA_RESCAN_WAIT in v3.11-rc1.

* btrfs.c [!BTRFS_IOC_QUOTA_RESCAN]
(struct btrfs_ioctl_quota_rescan_args): New structure.
(BTRFS_IOC_QUOTA_RESCAN, BTRFS_IOC_QUOTA_RESCAN_STATUS): New macros.
[!BTRFS_IOC_QUOTA_RESCAN_WAIT] (BTRFS_IOC_QUOTA_RESCAN_WAIT): New macro.
* tests/btrfs.c: Likewise.

Reported-by: Li Er <phoooyb@gmail.com>