xfs: update for 3.16-rc1 This update contains: o cleanup removing unused function args o rework of the filestreams allocator to use dentry cache parent lookups o new on-disk free inode btree and optimised inode allocator o various bug fixes o rework of internal attribute API o cleanup of superblock feature bit support to remove historic cruft o more fixes and minor cleanups o added a new directory/attribute geometry abstraction o yet more fixes and minor cleanups.