Format libstd with rustfmt

This commit applies rustfmt with rust-lang/rust's default settings to
files in src/libstd *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 -name '*.rs' \
        | xargs rustfmt --edition=2018 --unstable-features --skip-children
    $ rg libstd outstanding_files | xargs git checkout --

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

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, 5 insertions, 10 deletions

diff --git a/src/libstd/tests/env.rs b/src/libstd/tests/env.rs
index f8014cb2ad9..c94fc41178d 100644
--- a/src/libstd/tests/env.rs
+++ b/src/libstd/tests/env.rs
@@ -1,13 +1,12 @@
 use std::env::*;
-use std::ffi::{OsString, OsStr};
+use std::ffi::{OsStr, OsString};
 
-use rand::{thread_rng, Rng};
 use rand::distributions::Alphanumeric;
+use rand::{thread_rng, Rng};
 
 fn make_rand_name() -> OsString {
     let rng = thread_rng();
-    let n = format!("TEST{}", rng.sample_iter(&Alphanumeric).take(10)
-                                 .collect::<String>());
+    let n = format!("TEST{}", rng.sample_iter(&Alphanumeric).take(10).collect::<String>());
     let n = OsString::from(n);
     assert!(var_os(&n).is_none());
     n
@@ -73,11 +72,7 @@ fn test_env_set_var() {
 
     let mut e = vars_os();
     set_var(&n, "VALUE");
-    assert!(!e.any(|(k, v)| {
-        &*k == &*n && &*v == "VALUE"
-    }));
+    assert!(!e.any(|(k, v)| { &*k == &*n && &*v == "VALUE" }));
 
-    assert!(vars_os().any(|(k, v)| {
-        &*k == &*n && &*v == "VALUE"
-    }));
+    assert!(vars_os().any(|(k, v)| { &*k == &*n && &*v == "VALUE" }));
 }