Fix soundness hole in struct with expressions.

Fixes #18567. Struct{x:foo, .. with_expr} did not walk with_expr, which allowed
using moved variables in some cases.  The CFG for structs also built up with
with_expr happening before the fields, which is now reversed. (Fields are now
before the with_expr in the CFG)

src/test/compile-fail/walk-struct-literal-with.rs

@@ -0,0 +1,28 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+struct Mine{
+    test: String,
+    other_val: int
+}
+
+impl Mine{
+    fn make_string_bar(mut self) -> Mine{
+        self.test = "Bar".to_string();
+        self
+    }
+}
+
+fn main(){
+    let start = Mine{test:"Foo".to_string(), other_val:0};
+    let end = Mine{other_val:1, ..start.make_string_bar()};
+    println!("{}", start.test); //~ ERROR use of moved value: `start.test`
+}
+