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