Reformat use declarations.

The previous commit updated `rustfmt.toml` appropriately. This commit is
the outcome of running `x fmt --all` with the new formatting options.

compiler/rustc_log/src/lib.rs

@@ -41,12 +41,11 @@
 use std::env::{self, VarError};
 use std::fmt::{self, Display};
 use std::io::{self, IsTerminal};
+
 use tracing_core::{Event, Subscriber};
 use tracing_subscriber::filter::{Directive, EnvFilter, LevelFilter};
-use tracing_subscriber::fmt::{
-    format::{self, FormatEvent, FormatFields},
-    FmtContext,
-};
+use tracing_subscriber::fmt::format::{self, FormatEvent, FormatFields};
+use tracing_subscriber::fmt::FmtContext;
 use tracing_subscriber::layer::SubscriberExt;
 
 /// The values of all the environment variables that matter for configuring a logger.