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, 16 insertions, 10 deletions

diff --git a/src/libstd/rt.rs b/src/libstd/rt.rs
index 63e35d5ed91..1ed984509d2 100644
--- a/src/libstd/rt.rs
+++ b/src/libstd/rt.rs
@@ -6,21 +6,25 @@
 //! and should be considered as private implementation details for the
 //! time being.
 
-#![unstable(feature = "rt",
-            reason = "this public module should not exist and is highly likely \
-                      to disappear",
-            issue = "0")]
+#![unstable(
+    feature = "rt",
+    reason = "this public module should not exist and is highly likely \
+              to disappear",
+    issue = "0"
+)]
 #![doc(hidden)]
 
-
 // Re-export some of our utilities which are expected by other crates.
 pub use crate::panicking::{begin_panic, begin_panic_fmt, update_panic_count};
 
 // To reduce the generated code of the new `lang_start`, this function is doing
 // the real work.
 #[cfg(not(test))]
-fn lang_start_internal(main: &(dyn Fn() -> i32 + Sync + crate::panic::RefUnwindSafe),
-                       argc: isize, argv: *const *const u8) -> isize {
+fn lang_start_internal(
+    main: &(dyn Fn() -> i32 + Sync + crate::panic::RefUnwindSafe),
+    argc: isize,
+    argv: *const *const u8,
+) -> isize {
     use crate::panic;
     use crate::sys;
     use crate::sys_common;
@@ -55,8 +59,10 @@ fn lang_start_internal(main: &(dyn Fn() -> i32 + Sync + crate::panic::RefUnwindS
 
 #[cfg(not(test))]
 #[lang = "start"]
-fn lang_start<T: crate::process::Termination + 'static>
-    (main: fn() -> T, argc: isize, argv: *const *const u8) -> isize
-{
+fn lang_start<T: crate::process::Termination + 'static>(
+    main: fn() -> T,
+    argc: isize,
+    argv: *const *const u8,
+) -> isize {
     lang_start_internal(&move || main().report(), argc, argv)
 }