Provide NFSv4 server support (EXPERIMENTAL)

configname: CONFIG_NFSD_V4

Linux Kernel Configuration
└─>File systems
└─>Network File Systems
└─>Provide NFSv4 server support (EXPERIMENTAL)
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
If you would like to include the NFSv4 server as well as the NFSv2
and NFSv3 servers, say Y here. This feature is experimental, and
should only be used if you are interested in helping to test NFSv4.
If unsure, say N.