Update output for borrowck=migrate compare mode.

This commit updates the test output for the updated NLL compare mode
that uses `-Z borrowck=migrate` rather than `-Z borrowck=mir`. The
previous commit changes `compiletest` and this commit only updates
`.nll.stderr` files.

Author: davidtwco

src/test/ui/access-mode-in-closures.nll.stderr

@@ -13,6 +13,18 @@ note: move occurs because `v` has type `std::vec::Vec<isize>`, which does not im
 LL |         match *s { sty(v) => v } //~ ERROR cannot move out
    |                        ^
 
-error: aborting due to previous error
+error[E0507]: cannot move out of `s.0` which is behind a `&` reference
+  --> $DIR/access-mode-in-closures.rs:19:24
+   |
+LL |     let _foo = unpack(|s| {
+   |                        - help: consider changing this to be a mutable reference: `&mut sty`
+LL |         // Test that `s` is moved here.
+LL |         match *s { sty(v) => v } //~ ERROR cannot move out
+   |                        ^
+   |                        |
+   |                        cannot move out of `s.0` which is behind a `&` reference
+   |                        `s` is a `&` reference, so the data it refers to cannot be moved
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0507`.

src/test/ui/associated-types/associated-types-project-from-hrtb-in-fn-body.nll.stderr

@@ -32,6 +32,18 @@ error[E0507]: cannot move out of borrowed content
 LL |     *n;  //~ ERROR: cannot move out of borrowed content
    |     ^^ cannot move out of borrowed content
 
+error[E0507]: cannot move out of `*n` which is behind a `&` reference
+  --> $DIR/binop-move-semantics.rs:42:5
+   |
+LL |     let n = &y;
+   |             -- help: consider changing this to be a mutable reference: `&mut y`
+...
+LL |     *n;  //~ ERROR: cannot move out of borrowed content
+   |     ^^
+   |     |
+   |     cannot move out of `*n` which is behind a `&` reference
+   |     `n` is a `&` reference, so the data it refers to cannot be moved
+
 error[E0502]: cannot borrow `f` as immutable because it is also borrowed as mutable
   --> $DIR/binop-move-semantics.rs:64:5
    |
@@ -62,7 +74,7 @@ LL | |     &mut f;  //~ ERROR: cannot borrow `f` as mutable because it is also b
    |       |    immutable borrow later used here
    |       mutable borrow occurs here
 
-error: aborting due to 6 previous errors
+error: aborting due to 7 previous errors
 
 Some errors occurred: E0382, E0502, E0507.
 For more information about an error, try `rustc --explain E0382`.

src/test/ui/associated-types/associated-types-subtyping-1.nll.stderr

@@ -40,15 +40,19 @@ LL |     let c2 = || set(x); //~ ERROR two closures require unique access to `x`
 LL |     c1;
    |     -- first borrow later used here
 
-error[E0594]: cannot assign to `x`, as it is not declared as mutable
+warning[E0594]: cannot assign to `x`, as it is not declared as mutable
   --> $DIR/borrowck-closures-unique.rs:57:38
    |
 LL | fn e(x: &'static mut isize) {
    |      - help: consider changing this to be mutable: `mut x`
 LL |     let c1 = |y: &'static mut isize| x = y; //~ ERROR closure cannot assign to immutable argument
    |                                      ^^^^^ cannot assign
+   |
+   = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
+           It represents potential unsoundness in your code.
+           This warning will become a hard error in the future.
 
-error: aborting due to 4 previous errors
+error: aborting due to 3 previous errors
 
 Some errors occurred: E0500, E0524, E0594.
 For more information about an error, try `rustc --explain E0500`.