unix: add IoctlLoop{Get,Set}Status64 on linux
unix: add IoctlLoop{Get,Set}Status64 on linux

These ioctls are used to get/set the status of a loop device. See
https://man7.org/linux/man-pages/man4/loop.4.html for details.

Change-Id: Ia66db639e6d9326af79954eea5c8f7515aa171d1
Reviewed-on: https://go-review.googlesource.com/c/sys/+/425296
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Run-TryBot: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@google.com>
Auto-Submit: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@google.com>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@google.com>
Run-TryBot: Tobias Klauser <0a68dd4915066ec5d3f81f75a828fee53dcc8822@gmail.com>
Reviewed-by: Heschi Kreinick <e89ab2b172855aa0ad01c40c4d8a3535a61ac68a@google.com>

golang/sys,golang/sys,golang/sys