Fix crate paths in comments

src/librustc_feature/lib.rs

@@ -1,7 +1,8 @@
 //! # Feature gates
 //!
 //! This crate declares the set of past and present unstable features in the compiler.
-//! Feature gate checking itself is done in `libsyntax/feature_gate/check.rs` at the moment.
+//! Feature gate checking itself is done in `librustc_ast_passes/feature_gate.rs`
+//! at the moment.
 //!
 //! Features are enabled in programs via the crate-level attributes of
 //! `#![feature(...)]` with a comma-separated list of features.

src/librustc_lint/builtin.rs

@@ -1812,7 +1812,7 @@ declare_lint! {
 }
 
 declare_lint_pass!(
-    /// Check for used feature gates in `INCOMPLETE_FEATURES` in `feature_gate.rs`.
+    /// Check for used feature gates in `INCOMPLETE_FEATURES` in `librustc_feature/active.rs`.
     IncompleteFeatures => [INCOMPLETE_FEATURES]
 );
 

src/test/ui/feature-gate/issue-43106-gating-of-builtin-attrs.rs

@@ -12,7 +12,7 @@
 // the change when it happens.
 //
 // At the time of authoring, the attributes here are listed in the
-// order that they occur in libsyntax/feature_gate.rs.
+// order that they occur in `librustc_feature`.
 //
 // Any builtin attributes that:
 //