rename rustc_attr to rustc_attr_parsing and create rustc_attr_data_structures

compiler/rustc_attr_data_structures/src/lib.rs

@@ -0,0 +1,16 @@
+// tidy-alphabetical-start
+#![allow(internal_features)]
+#![doc(rust_logo)]
+#![feature(let_chains)]
+#![feature(rustdoc_internals)]
+#![warn(unreachable_pub)]
+// tidy-alphabetical-end
+
+mod attributes;
+mod stability;
+mod version;
+
+pub use attributes::*;
+pub(crate) use rustc_session::HashStableContext;
+pub use stability::*;
+pub use version::*;