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

1 files changed, 8 insertions, 8 deletions

diff --git a/src/libstd/sys/wasm/thread.rs b/src/libstd/sys/wasm/thread.rs
index d06965f3278..0e0e78a8276 100644
--- a/src/libstd/sys/wasm/thread.rs
+++ b/src/libstd/sys/wasm/thread.rs
@@ -9,9 +9,7 @@ pub const DEFAULT_MIN_STACK_SIZE: usize = 4096;
 
 impl Thread {
     // unsafe: see thread::Builder::spawn_unchecked for safety requirements
-    pub unsafe fn new(_stack: usize, _p: Box<dyn FnOnce()>)
-        -> io::Result<Thread>
-    {
+    pub unsafe fn new(_stack: usize, _p: Box<dyn FnOnce()>) -> io::Result<Thread> {
         unsupported()
     }
 
@@ -55,8 +53,12 @@ impl Thread {
 
 pub mod guard {
     pub type Guard = !;
-    pub unsafe fn current() -> Option<Guard> { None }
-    pub unsafe fn init() -> Option<Guard> { None }
+    pub unsafe fn current() -> Option<Guard> {
+        None
+    }
+    pub unsafe fn init() -> Option<Guard> {
+        None
+    }
 }
 
 // This is only used by atomics primitives when the `atomics` feature is
@@ -84,9 +86,7 @@ pub fn my_id() -> u32 {
         if MY_ID == 0 {
             let mut cur = NEXT_ID.load(SeqCst);
             MY_ID = loop {
-                let next = cur.checked_add(1).unwrap_or_else(|| {
-                    crate::arch::wasm32::unreachable()
-                });
+                let next = cur.checked_add(1).unwrap_or_else(|| crate::arch::wasm32::unreachable());
                 match NEXT_ID.compare_exchange(cur, next, SeqCst, SeqCst) {
                     Ok(_) => break next,
                     Err(i) => cur = i,