Consider switching `cfg-if` to `cfg_select!`

[polarathene]

cfg_select! was stabilized for Rust 1.95, at some point it might be worth replacing the current cfg-if dependency in favour of that? (although this would require a rust-version = "1.95" addition to the Cargo.toml, preventing earlier toolchains from getting any new updates?)

The cfg_if usage is only covered here:

dlmalloc-rs/src/lib.rs

Lines 76 to 93 in 852bee3

	cfg_if::cfg_if! {
	if #[cfg(target_family = "wasm")] {
	#[path = "wasm.rs"]
	mod sys;
	} else if #[cfg(target_os = "windows")] {
	#[path = "windows.rs"]
	mod sys;
	} else if #[cfg(target_os = "xous")] {
	#[path = "xous.rs"]
	mod sys;
	} else if #[cfg(any(target_os = "linux", target_os = "macos"))] {
	#[path = "unix.rs"]
	mod sys;
	} else {
	#[path = "dummy.rs"]
	mod sys;
	}
	}