dpi: remove interior mutability

Make Dpi a copy type and keep interior mutability in the Handle
7 jobs from defs in 18 minutes and 48 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #186046
fedora test

00:08:25

 
  Lint
manual #186048
allowed to fail manual
clippy
failed #186047
rustfmt

00:00:25

passed #186049
tarball

00:10:22

 
  Cross Distro
skipped #186052
debian_i386:testing
skipped #186051
debian:testing
skipped #186050
fedora:rawhide
 
Name Stage Failure
failed
rustfmt Lint
-        Dpi {
- x,
- y,
- }
+ Dpi { x, y }
}

pub fn x(&self) -> f64 {
ERROR: Job failed: exit code 1