Remove dead recursive partial eq impl

Its nowhere used (if it had been used used, the rust stack would have overflown
due to the recursion). Its presence was confusing for mrustc.

src/librustc_data_structures/accumulate_vec.rs

@@ -25,7 +25,7 @@ use rustc_serialize::{Encodable, Encoder, Decodable, Decoder};
 
 use array_vec::{self, Array, ArrayVec};
 
-#[derive(PartialEq, Eq, Hash, Debug)]
+#[derive(Hash, Debug)]
 pub enum AccumulateVec<A: Array> {
     Array(ArrayVec<A>),
     Heap(Vec<A::Element>)

src/librustc_data_structures/array_vec.rs

@@ -52,14 +52,6 @@ impl<A> Hash for ArrayVec<A>
     }
 }
 
-impl<A: Array> PartialEq for ArrayVec<A> {
-    fn eq(&self, other: &Self) -> bool {
-        self == other
-    }
-}
-
-impl<A: Array> Eq for ArrayVec<A> {}
-
 impl<A> Clone for ArrayVec<A>
     where A: Array,
           A::Element: Clone {