filesystems/gvfs: Add option to use fuser(1) in place of lsof(1)

[madpilot]

Summary

gvfs has an hard dependency on lsof(1), due to the code using it in just one place to lookup PIDS for programs preventing a removable disk unmount.

lsof(1) is a problematic port, often breaking on head. furthermore, gvfs is depended upon by many desktop environments and programs, causing lsoif to be nstalled on many machines, for just this single internal usage scenario.

We do have fuser(1) in base that provides the required functionality. This patch, also submitted upstream [1] allows us to shed this hard dependency, und use fuser(1) to get the list of pids.

I think this would be a big improvement for many users.

[1] https://gitlab.gnome.org/GNOME/gvfs/-/merge_requests/321

Test Plan

I'm running this patch with XFCE and everything looks fine. Maybe some testing by toher DE users could be useful.

[glebius]

Guido, thanks a lot for working on that!

[madpilot]

I did get some feedback in the upstream review and updated the upstream patch.

I'm aligning the patch here, and adaping the Makefile to it with this patch update.

[madpilot]

(Sorry, I sent this update by mistake)

[madpilot]

My patch has been merged upstream (with some changes) [1]

I'm updating this review with a patch reproducing what has been merged.

Since this cahnge is now included upstream and will be in a future
stable release, I'd really like to get approval to update the ports
tree.

Thanks in advance!

[1] https://gitlab.gnome.org/GNOME/gvfs/-/commit/68f26fdfd9fcbe3af4fcdb63b91cdad90037f1c2 and following ones

[fluffy]

LGTM