fix: cargo clippy warning and error

[rtczza]

clippy tips:

error[E0308]: mismatched types
   --> src/c_interface.rs:436:14
    |
433 | pub extern "C" fn sysinfo_process_parent_pid(process: CProcess) -> PID {
    |                                                                    --- expected `i32` because of return type
...
436 |     unsafe { (*process).parent().unwrap_or(Pid(0)).0 }
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `usize`
    |
help: you can convert a `usize` to an `i32` and panic if the converted value doesn't fit
    |
436 |     unsafe { (*process).parent().unwrap_or(Pid(0)).0.try_into().unwrap() }
    |                                                     ++++++++++++++++++++

For more information about this error, try `rustc --explain E0308`.

and :

warning: returning the result of a `let` binding from a block
   --> src/c_interface.rs:638:5
    |
633 | /     let c_string = if let Some(c) = System::long_os_version().and_then(|c| CString::new(c).ok()) {
634 | |         c.into_raw() as _
635 | |     } else {
636 | |         std::ptr::null()
637 | |     };
    | |______- unnecessary `let` binding
638 |       c_string
    |       ^^^^^^^^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_and_return
    = note: `#[warn(clippy::let_and_return)]` on by default
help: return the expression directly
    |
633 ~     
634 ~     if let Some(c) = System::long_os_version().and_then(|c| CString::new(c).ok()) {
635 +         c.into_raw() as _
636 +     } else {
637 +         std::ptr::null()
638 +     }
    |

[GuillaumeGomez]

For all these cases, as _ should be enough.

[rtczza]

Ok, resubmitted.

[GuillaumeGomez]

Nice! 👍

[GuillaumeGomez]

Please run cargo fmt now to make CI happy then I'll merge.

[GuillaumeGomez]

Thanks!