style: use field init shorthand

This is so that all `::new` functions are padronized. The `Arc`
implementation in the book already does this.

src/exception-safety.md

@@ -161,9 +161,9 @@ impl<'a, T> Hole<'a, T> {
         unsafe {
             let elt = ptr::read(&data[pos]);
             Hole {
-                data: data,
+                data,
                 elt: Some(elt),
-                pos: pos,
+                pos,
             }
         }
     }

src/leaking.md

@@ -134,10 +134,10 @@ impl<T> Rc<T> {
             // Wouldn't it be nice if heap::allocate worked like this?
             let ptr = heap::allocate::<RcBox<T>>();
             ptr::write(ptr, RcBox {
-                data: data,
+                data,
                 ref_count: 1,
             });
-            Rc { ptr: ptr }
+            Rc { ptr }
         }
     }
 

src/vec/vec-final.md

@@ -23,7 +23,7 @@ impl<T> RawVec<T> {
         // `NonNull::dangling()` doubles as "unallocated" and "zero-sized allocation"
         RawVec {
             ptr: NonNull::dangling(),
-            cap: cap,
+            cap,
         }
     }
 

src/vec/vec-zsts.md

@@ -39,7 +39,7 @@ impl<T> RawVec<T> {
         // `NonNull::dangling()` doubles as "unallocated" and "zero-sized allocation"
         RawVec {
             ptr: NonNull::dangling(),
-            cap: cap,
+            cap,
         }
     }