nfs4: make sure we have inode names required to get file handle
nfs4: minor improvements in VnodeToInode code * removal of now unnecessary NULL check * Clear() is Replace(NULL)
nfs4: use exponential backoff when the server ask to wait
nfs4: fix incrementing owner sequence id in some cases

If in a compound request an error occurs before the operation that takes
sequence id is executed (e.g. OPEN or LOCK) do not increment sequence id
regardless of the error code.
Merge branch 'nfs4'
nfs4: silent "suggest parentheses" GCC warning