Rollup merge of #103117 - joshtriplett:use-is-terminal, r=eholk

Use `IsTerminal` in place of `atty`

In any crate that can use nightly features, use `IsTerminal` rather than
`atty`:

- Use `IsTerminal` in `rustc_errors`
- Use `IsTerminal` in `rustc_driver`
- Use `IsTerminal` in `rustc_log`
- Use `IsTerminal` in `librustdoc`

diff --cc Cargo.lock
Simple merge

diff --cc compiler/rustc_driver/src/lib.rs
index e043368fdfe0210ae475bd7b151310538ba099cc,d1d590d2d08ddd47eb751b50006aea0b6f2a20b8..8a712cec85211b0a9c1936c83b586350a74537dd
--- 1/compiler/rustc_driver/src/lib.rs
--- 2/compiler/rustc_driver/src/lib.rs
+++ b/compiler/rustc_driver/src/lib.rs
@@@ -5,8 -5,8 +5,9 @@@
  //! This API is completely unstable and subject to change.
  
  #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
+ #![feature(is_terminal)]
  #![feature(once_cell)]
 +#![feature(decl_macro)]
  #![recursion_limit = "256"]
  #![allow(rustc::potential_query_instability)]
  #![deny(rustc::untranslatable_diagnostic)]

diff --cc compiler/rustc_errors/Cargo.toml
Simple merge

diff --cc compiler/rustc_errors/src/emitter.rs
Simple merge

diff --cc compiler/rustc_errors/src/lib.rs
Simple merge

diff --cc src/librustdoc/Cargo.toml
Simple merge

diff --cc src/librustdoc/lib.rs
Simple merge