Some NFSV4.1 servers, such as AmazonEFS, have very low limits for the number of
OpenOwners. As such, the default of an OpenOwner/process can easily exceed this
limit. Since NFSv4.1 allows multiple concurrent Opens on an OpenOwner, using a
single OpenOwner for all Opens is practical.
This patch (still experimental) does this via a new NFS mount option called "oneopenown"
which can only be applied to NFSv4.1 mounts.