Tidy fixup

Author: oli-obk

src/libsyntax/feature_gate.rs

@@ -492,7 +492,7 @@ declare_features! (
 
     // `extern crate self as foo;` puts local crate root into extern prelude under name `foo`.
     (active, extern_crate_self, "1.31.0", Some(56409), None),
-    
+
     // Allows calling `const unsafe fn` inside `unsafe` blocks in `const fn` functions.
     (active, min_const_unsafe_fn, "1.31.0", Some(55607), None),
 );