remove unused imports

This PR should remove clippy warnings.

Author: stlankes

hermit-abi/src/lib.rs

@@ -10,8 +10,6 @@ pub mod errno;
 pub mod tcplistener;
 pub mod tcpstream;
 
-use core::mem::MaybeUninit;
-
 use core::ffi::{c_int, c_void};
 
 /// A thread handle type