xfs: update for 3.17-rc1

This update contains:
o conversion of the XFS core to pass negative error numbers
o restructing of core XFS code that is shared with userspace to fs/xfs/libxfs
o introduction of sysfs interface for XFS
o bulkstat refactoring
o demand driven speculative preallocation removal
o XFS now always requires 64 bit sectors to be configured
o metadata verifier changes to ensure CRCs are calculated during log recovery
o various minor code cleanups
o miscellaneous bug fixes
Merge branch 'xfs-misc-fixes-3.17-2' into for-next