Re-export more rustc_span::symbol things from rustc_span.

`rustc_span::symbol` defines some things that are re-exported from
`rustc_span`, such as `Symbol` and `sym`. But it doesn't re-export some
closely related things such as `Ident` and `kw`. So you can do `use
rustc_span::{Symbol, sym}` but you have to do `use
rustc_span::symbol::{Ident, kw}`, which is inconsistent for no good
reason.

This commit re-exports `Ident`, `kw`, and `MacroRulesNormalizedIdent`,
and changes many `rustc_span::symbol::` qualifiers in `compiler/` to
`rustc_span::`. This is a 200+ net line of code reduction, mostly
because many files with two `use rustc_span` items can be reduced to
one.

compiler/rustc_hir/src/definitions.rs

@@ -11,7 +11,7 @@ use rustc_data_structures::stable_hasher::{Hash64, StableHasher};
 use rustc_data_structures::unord::UnordMap;
 use rustc_index::IndexVec;
 use rustc_macros::{Decodable, Encodable};
-use rustc_span::symbol::{Symbol, kw, sym};
+use rustc_span::{Symbol, kw, sym};
 use tracing::{debug, instrument};
 
 pub use crate::def_id::DefPathHash;

compiler/rustc_hir/src/hir.rs

@@ -20,8 +20,7 @@ use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::def_id::LocalDefId;
 use rustc_span::hygiene::MacroKind;
 use rustc_span::source_map::Spanned;
-use rustc_span::symbol::{Ident, Symbol, kw, sym};
-use rustc_span::{BytePos, DUMMY_SP, ErrorGuaranteed, Span};
+use rustc_span::{BytePos, DUMMY_SP, ErrorGuaranteed, Ident, Span, Symbol, kw, sym};
 use rustc_target::asm::InlineAsmRegOrRegClass;
 use smallvec::SmallVec;
 use thin_vec::ThinVec;

compiler/rustc_hir/src/intravisit.rs

@@ -66,9 +66,8 @@
 
 use rustc_ast::Label;
 use rustc_ast::visit::{VisitorResult, try_visit, visit_opt, walk_list};
-use rustc_span::Span;
 use rustc_span::def_id::LocalDefId;
-use rustc_span::symbol::{Ident, Symbol};
+use rustc_span::{Ident, Span, Symbol};
 
 use crate::hir::*;
 

compiler/rustc_hir/src/lang_items.rs

@@ -11,8 +11,7 @@ use rustc_ast::attr::AttributeExt;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
-use rustc_span::Span;
-use rustc_span::symbol::{Symbol, kw, sym};
+use rustc_span::{Span, Symbol, kw, sym};
 
 use crate::def_id::DefId;
 use crate::{MethodKind, Target};

compiler/rustc_hir/src/pat_util.rs

@@ -1,7 +1,6 @@
 use std::iter::Enumerate;
 
-use rustc_span::Span;
-use rustc_span::symbol::Ident;
+use rustc_span::{Ident, Span};
 
 use crate::def::{CtorOf, DefKind, Res};
 use crate::def_id::{DefId, DefIdSet};

compiler/rustc_hir/src/weak_lang_items.rs

@@ -1,6 +1,6 @@
 //! Validity checking for weak lang items
 
-use rustc_span::symbol::{Symbol, sym};
+use rustc_span::{Symbol, sym};
 
 use crate::LangItem;