xfs: update for 3.15-rc1

The main changes in the XFS tree for 3.15-rc1 are:

        - O_TMPFILE support
        - allowing AIO+DIO writes beyond EOF
        - FALLOC_FL_COLLAPSE_RANGE support for fallocate syscall and XFS
          implementation
        - FALLOC_FL_ZERO_RANGE support for fallocate syscall and XFS
          implementation
        - IO verifier cleanup and rework
        - stack usage reduction changes
        - vm_map_ram NOIO context fixes to remove lockdep warings
        - various bug fixes and cleanups
Merge branch 'xfs-bug-fixes-for-3.15-3' into for-next