Add DragonFly support via FreeBSD codepath

DragonFly has `getmntinfo` for `statfs` and `getmntvinfo` for `statvfs`.
Use `statfs` variant for compatibility with FreeBSD and OpenBSD.

error[E0425]: cannot find function `get_mount_points` in this scope
  --> czkawka-6.0.0/cargo-crates/trash-3.0.2/src/freedesktop.rs:31:28
   |
31 |         let mount_points = get_mount_points()?;
   |                            ^^^^^^^^^^^^^^^^ not found in this scope

error[E0425]: cannot find function `get_mount_points` in this scope
  --> czkawka-6.0.0/cargo-crates/trash-3.0.2/src/freedesktop.rs:80:24
   |
80 |     let mount_points = get_mount_points()?;
   |                        ^^^^^^^^^^^^^^^^ not found in this scope

Cargo.toml

@@ -41,7 +41,7 @@ scopeguard = "1.2.0"
 url = "2.4.1"
 once_cell = "1.18.0"
 
-[target.'cfg(any(target_os = "freebsd", target_os = "openbsd", target_os = "netbsd"))'.dependencies]
+[target.'cfg(any(target_os = "dragonfly", target_os = "freebsd", target_os = "netbsd", target_os = "openbsd"))'.dependencies]
 once_cell = "1.7.2"
 
 [target.'cfg(windows)'.dependencies]

src/freedesktop.rs

@@ -678,7 +678,7 @@ fn get_mount_points() -> Result<Vec<MountPoint>, Error> {
     Ok(result)
 }
 
-#[cfg(any(target_os = "freebsd", target_os = "openbsd"))]
+#[cfg(any(target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd"))]
 fn get_mount_points() -> Result<Vec<MountPoint>, Error> {
     use once_cell::sync::Lazy;
     use std::sync::Mutex;