Enable *bsd collector on darwin

[discordianfish]

Well that was easy :)

The cgo based bsd variant just works on darwin:

$ curl -s 192.168.1.104:9100/metrics|grep '/dev/disk1'
node_filesystem_avail{device="/dev/disk1",fstype="hfs",mountpoint="/"} 7.5835293696e+10
node_filesystem_files{device="/dev/disk1",fstype="hfs",mountpoint="/"} 5.8315941e+07
node_filesystem_files_free{device="/dev/disk1",fstype="hfs",mountpoint="/"} 1.8514476e+07
node_filesystem_free{device="/dev/disk1",fstype="hfs",mountpoint="/"} 7.6097437696e+10
node_filesystem_readonly{device="/dev/disk1",fstype="hfs",mountpoint="/"} 0
node_filesystem_size{device="/dev/disk1",fstype="hfs",mountpoint="/"} 2.38862102528e+11

[juliusv]

👍

[grobie]

👍 after fixing the error.

[SuperQ]

Nice