Change HirVec<P<T>> to HirVec<T> in Expr.

This changes structures like this:
```
[ ExprArray | 8 | P ]
                  |
                  v
                  [ P | P | P | P | P | P | P | P ]
                    |
                    v
                    [ ExprTup | 2 | P ]
                                    |
                                    v
                                    [ P | P ]
                                      |
                                      v
                                      [ Expr ]
```
to this:
```
[ ExprArray | 8 | P ]
                  |
                  v
                  [ [ ExprTup | 2 | P ] | ... ]
                                    |
                                    v
                                    [ Expr | Expr ]
```
diff --git a/src/librustc/cfg/construct.rs b/src/librustc/cfg/construct.rs
index 22c7d14..be996ea 100644
--- a/src/librustc/cfg/construct.rs
+++ b/src/librustc/cfg/construct.rs
@@ -299,15 +299,15 @@
             }
 
             hir::ExprArray(ref elems) => {
-                self.straightline(expr, pred, elems.iter().map(|e| &**e))
+                self.straightline(expr, pred, elems.iter().map(|e| &*e))
             }
 
             hir::ExprCall(ref func, ref args) => {
-                self.call(expr, pred, &func, args.iter().map(|e| &**e))
+                self.call(expr, pred, &func, args.iter().map(|e| &*e))
             }
 
             hir::ExprMethodCall(.., ref args) => {
-                self.call(expr, pred, &args[0], args[1..].iter().map(|e| &**e))
+                self.call(expr, pred, &args[0], args[1..].iter().map(|e| &*e))
             }
 
             hir::ExprIndex(ref l, ref r) |
@@ -320,7 +320,7 @@
             }
 
             hir::ExprTup(ref exprs) => {
-                self.straightline(expr, pred, exprs.iter().map(|e| &**e))
+                self.straightline(expr, pred, exprs.iter().map(|e| &*e))
             }
 
             hir::ExprStruct(_, ref fields, ref base) => {
@@ -353,8 +353,8 @@
             }
 
             hir::ExprInlineAsm(_, ref outputs, ref inputs) => {
-                let post_outputs = self.exprs(outputs.iter().map(|e| &**e), pred);
-                let post_inputs = self.exprs(inputs.iter().map(|e| &**e), post_outputs);
+                let post_outputs = self.exprs(outputs.iter().map(|e| &*e), pred);
+                let post_inputs = self.exprs(inputs.iter().map(|e| &*e), post_outputs);
                 self.add_ast_node(expr.id, &[post_inputs])
             }