Fix pkgin detection on NetBSD 6 and 7 (#15834)

Since this is now the default package manager, it got moved
to another location on Netbsd :

  netbsd# type pkgin
  pkgin is a tracked alias for /usr/pkg/bin/pkgin
  netbsd# uname -a
  NetBSD netbsd.example.org 6.1.4 NetBSD 6.1.4 (GENERIC) amd64

But since the package manager is also used outside of NetBSD, we
have to keep the /opt/local path too.

lib/ansible/module_utils/facts.py

@@ -156,6 +156,7 @@ class Facts(object):
                  { 'path' : '/usr/sbin/urpmi',      'name' : 'urpmi' },
                  { 'path' : '/usr/bin/pacman',      'name' : 'pacman' },
                  { 'path' : '/bin/opkg',            'name' : 'opkg' },
+                 { 'path' : '/usr/pkg/bin/pkgin',   'name' : 'pkgin' },
                  { 'path' : '/opt/local/bin/pkgin', 'name' : 'pkgin' },
                  { 'path' : '/opt/local/bin/port',  'name' : 'macports' },
                  { 'path' : '/usr/local/bin/brew',  'name' : 'homebrew' },