DependencyList: remove outdated comment

Author: klensy

compiler/rustc_middle/src/middle/dependency_format.rs

@@ -10,9 +10,6 @@ use rustc_session::config::CrateType;
 /// A list of dependencies for a certain crate type.
 ///
 /// The length of this vector is the same as the number of external crates used.
-/// The value is None if the crate does not need to be linked (it was found
-/// statically in another dylib), or Some(kind) if it needs to be linked as
-/// `kind` (either static or dynamic).
 pub type DependencyList = Vec<Linkage>;
 
 /// A mapping of all required dependencies for a particular flavor of output.