deskutils/sysctlview: Update to 1.5.1

• The sysctlinfo interface (sysutils/sysctlinfo-kmod) is now required as build/run dependency which relies on the "oid_label" constant that was introduced in FreeBSD 1200019.
  
  Thus set the port to IGNORE if the above doesn't apply while I'm here. [1]

Changelog:

• Show nodes up to CTL_MAXNAME (24) levels
• Show the right value of the nodes without the last name
• Show a subtree without leaves (the nodes are all CTLTYPE_NODE)
• The sysctlinfo interface is 30% more efficient than the kernel undocumented interface [1]

PR: 240391
Submitted by: Alfonso S. Siciliano <alfix86@gmail.com> (maintainer)