Format libstd/sys with rustfmt

This commit applies rustfmt with rust-lang/rust's default settings to
files in src/libstd/sys *that are not involved in any currently open PR*
to minimize merge conflicts. THe list of files involved in open PRs was
determined by querying GitHub's GraphQL API with this script:
https://gist.github.com/dtolnay/aa9c34993dc051a4f344d1b10e4487e8

With the list of files from the script in outstanding_files, the
relevant commands were:

    $ find src/libstd/sys -name '*.rs' \
        | xargs rustfmt --edition=2018 --unstable-features --skip-children
    $ rg libstd/sys outstanding_files | xargs git checkout --

Repeating this process several months apart should get us coverage of
most of the rest of the files.

To confirm no funny business:

    $ git checkout $THIS_COMMIT^
    $ git show --pretty= --name-only $THIS_COMMIT \
        | xargs rustfmt --edition=2018 --unstable-features --skip-children
    $ git diff $THIS_COMMIT  # there should be no difference

Author: dtolnay

src/libstd/sys/cloudabi/os.rs

@@ -18,9 +18,7 @@ pub fn errno() -> i32 {
 pub fn error_string(errno: i32) -> String {
     // cloudlibc's strerror() is guaranteed to be thread-safe. There is
     // thus no need to use strerror_r().
-    str::from_utf8(unsafe { CStr::from_ptr(libc::strerror(errno)) }.to_bytes())
-        .unwrap()
-        .to_owned()
+    str::from_utf8(unsafe { CStr::from_ptr(libc::strerror(errno)) }.to_bytes()).unwrap().to_owned()
 }
 
 pub fn exit(code: i32) -> ! {

src/libstd/sys/cloudabi/shims/fs.rs

@@ -1,7 +1,7 @@
 use crate::ffi::OsString;
 use crate::fmt;
 use crate::hash::{Hash, Hasher};
-use crate::io::{self, SeekFrom, IoSlice, IoSliceMut};
+use crate::io::{self, IoSlice, IoSliceMut, SeekFrom};
 use crate::path::{Path, PathBuf};
 use crate::sys::time::SystemTime;
 use crate::sys::{unsupported, Void};