adds missing types, consts, and extern C refs for reading characters …

[TheNotary]

…immediately from terminal

A rust POC that uses this patch can be found here: https://github.com/TheNotary/another-rust-terminal-app

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[TheNotary]

When running cd libc-test; cargo test I get the below errors which I don't believe are related to this patch:

error: unnecessary parentheses around closure body
--> libc-test/build.rs:3210:33
|
3210 | cfg.skip_static(move |name| (name == "__dso_handle"));
| ^ ^
|
note: the lint level is defined here
--> libc-test/build.rs:1:9
|
1 | #![deny(warnings)]
| ^^^^^^^^
= note: #[deny(unused_parens)] implied by #[deny(warnings)]
help: remove these parentheses
|
3210 - cfg.skip_static(move |name| (name == "__dso_handle"));
3210 + cfg.skip_static(move |name| name == "__dso_handle");
|
error: could not compile libc-test (build script) due to 1 previous error
warning: build failed, waiting for other jobs to finish...

[Arshia001]

Thanks for this contribution, @TheNotary!

I've mentioned a couple of things I think don't align with wasix-libc. Also, the changes need to be moved to src/wasi/wasix.mod, which is for WASIX-specific functionality. src/wasi/mod.rs is for functionality that's common between WASI preview 1 and WASIX.

[TheNotary]

Thanks for the review, I've updated this PR. Could you link your reference for the remark regarding wasix-libc and typedef unsigned int speed_t;?