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, 5 deletions

diff --git a/src/libstd/collections/mod.rs b/src/libstd/collections/mod.rs
index f5957466be8..522b8b25144 100644
--- a/src/libstd/collections/mod.rs
+++ b/src/libstd/collections/mod.rs
@@ -413,20 +413,20 @@
 #[doc(hidden)]
 pub use crate::ops::Bound;
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc_crate::collections::{BinaryHeap, BTreeMap, BTreeSet};
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use alloc_crate::collections::{LinkedList, VecDeque};
-#[stable(feature = "rust1", since = "1.0.0")]
 pub use alloc_crate::collections::{binary_heap, btree_map, btree_set};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use alloc_crate::collections::{linked_list, vec_deque};
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use alloc_crate::collections::{BTreeMap, BTreeSet, BinaryHeap};
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use alloc_crate::collections::{LinkedList, VecDeque};
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::hash_map::HashMap;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::hash_set::HashSet;
 
-#[unstable(feature = "try_reserve", reason = "new API", issue="48043")]
+#[unstable(feature = "try_reserve", reason = "new API", issue = "48043")]
 pub use alloc_crate::collections::TryReserveError;
 
 mod hash;