Report Wired memory on FreeBSD

[theory14]

Feature Request

One of the typically reported memory usage classifications on FreeBSD is "wired memory". See https://wiki.freebsd.org/Memory for info on memory classifications. Telegraf does not currently report this value though gopsutil does gather it.

Proposal:

Update telegraf to report wired memory on FreeBSD. The data is already gathered by gopsutil and from what I can tell, only a single line of telegraf code is needed to expose this data.

I tested this briefly by adding:

"wired": vm.Wired,

to the fields map in the Gather function in plugins/inputs/system/memory.go and it worked fine on a very quick inspection.

Current behavior:

Wired memory is not reported by telegraf.

Desired behavior:

Wired memory to be reported by telegraf.

Use case: [Why is this important (helps with prioritizing requests)]

Providing a complete view of memory usage on FreeBSD machines. This appears (to me at least) to be a simple one line update, so I hope the level of effort to include is minimal.