Revision 495780

New port: sysutils/nsysctl: New sysctl utility with libxo and extra options

nsysctl (new sysctl) is a sysctl(8) utility clone to get or set kernel
state with libxo, sysctlmibinfo and extra options; improvements:

 * sysctlmibinfo(3) provides a simple API to the sysctl MIB,
 * all code about "opaque values" is in opaque.c,
 * output via libxo(3) in human and machine readable formats,
 * output is explicitly indicated by the options,
 * new option -D show all properties,
 * update option -e specific sep as a separator,
 * new option -F show flags,
 * new option -I show internal nodes,
 * new option -l show label,
 * new option -r show tag-root with libxo,
 * new option -m show format string,
 * delete option -n simply do not use -N,
 * updated option -N force to show name,
 * new option -p show [property-name]: property-value,
 * new option -S show magic nodes with -a,
 * new option -V if "showable" display value, otherwise hide the state,
 * new option -v force to show value,
 * new option -y show id.

WWW: https://gitlab.com/alfix/nsysctl/

PR:	        235870
Submitted by:	Alfonso S. Siciliano <alfix86@gmail.com>
Reviewed by:	mat
Approved by:	mat (mentor)
Differential Revision:	https://reviews.freebsd.org/D19469