xfs: update for 4.7-rc1

Changes in this update:
o fixes for mount line parsing, sparse warnings, read-only compat
  feature remount behaviour
o allow fast path symlink lookups for inline symlinks.
o attribute listing cleanups
o writeback goes direct to bios rather than indirecting through
  bufferheads
o transaction allocation cleanup
o optimised kmem_realloc
o added configurable error handling for metadata write errors,
  changed default error handling behaviour from "retry forever" to
  "retry until unmount then fail"
o fixed several inode cluster writeback lookup vs reclaim race
  conditions
o fixed inode cluster writeback checking wrong inode after lookup
o fixed bugs where struct xfs_inode freeing wasn't actually RCU safe
o cleaned up inode reclaim tagging
Merge branch 'xfs-4.7-inode-reclaim' into for-next