remove superfluous pinning of Unpin types and exploits of the pin! macro

[Morgane55440]

the pinning of [u8], str, Cstr, and similar types, is pointless as these types are Unpin
pinning an Unpin type does nothing at all. a Pin<&mut [u8]> behaves exactly the same as a &mut [u8] in all ways that matter.

but this is not really a problem.
what is a problem is the use of the pin! macro in this codebase.
the pin! macro has a bug, and this code was (most likely by mistake) abusing that bug.
thankfully, due to the fact all the types in play are Unpin, this was not a real problem, but because this bug is being fixed, your code will soon stop compiling.
in order tomake sure your code keeps compiling in the future, please merge this PR, which removes the exploits without modifying any behavior.

link to the fix PR in the compiler : rust-lang/rust#153457

[theemathas]

For context, pin!() is supposed to consume a value of type T and produce a value of type Pin<&mut T>. Due to a bug, for a few rust versions, it was sometimes turning a &mut T into a Pin<&mut T> or turning a &T into a Pin<&T> instead.

For reference, here's the build output of your code on the beta version of Rust, which will be released as stable Rust 1.97.0. Your code will fail to compile with this version of Rust. https://crater-reports.s3.amazonaws.com/beta-1.97-3-v2/1.97.0-beta.1/gh/rockwotj.tigerdns/log.txt

Please refer to the documentation for the correct usage of Pin: https://doc.rust-lang.org/std/pin/index.html

Sorry for the inconvenience.