nfsstat: Add libxo output

Add libxo output support
Merge exp41_intpr and exp_intpr function. The only difference is to print
NFSV4.1 operations in exp41, add a third arguement to control that.
printtitle was set to 1 and don't have a switch, add a -q options to control it.

Reviewed by: bapt
Sponsored by: Gandi.net
Differential Revision: https://reviews.freebsd.org/D14012