Removed ignore-test-compare-mode-nll from unboxed-closures tests

by strengthening the tests (by adding no-op references to the
closures doing the borrows after the conflicting borrows, thus
forcing the lifetimes to resemble lexical scopes even under NLL).

Author: pnkfelix

src/test/ui/unboxed-closures/unboxed-closure-region.nll.stderr

@@ -0,0 +1,15 @@
+error[E0597]: `x` does not live long enough
+  --> $DIR/unboxed-closure-region.rs:18:12
+   |
+LL |         || x //~ ERROR `x` does not live long enough
+   |         -- ^ borrowed value does not live long enough
+   |         |
+   |         value captured here
+LL |     };
+   |     - `x` dropped here while still borrowed
+LL |     _f;
+   |     -- borrow later used here
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0597`.

src/test/ui/unboxed-closures/unboxed-closure-region.rs

@@ -8,13 +8,14 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// ignore-compare-mode-nll
-
 // Test that an unboxed closure that captures a free variable by
 // reference cannot escape the region of that variable.
+
+
 fn main() {
     let _f = {
         let x = 0;
         || x //~ ERROR `x` does not live long enough
     };
+    _f;
 }

src/test/ui/unboxed-closures/unboxed-closure-region.stderr

@@ -7,6 +7,7 @@ LL |         || x //~ ERROR `x` does not live long enough
    |         capture occurs here
 LL |     };
    |     - borrowed value only lives until here
+LL |     _f;
 LL | }
    | - borrowed value needs to live until here
 

src/test/ui/unboxed-closures/unboxed-closures-borrow-conflict.nll.stderr

@@ -0,0 +1,15 @@
+error[E0503]: cannot use `x` because it was mutably borrowed
+  --> $DIR/unboxed-closures-borrow-conflict.rs:19:14
+   |
+LL |     let f = || x += 1;
+   |             -- - borrow occurs due to use of `x` in closure
+   |             |
+   |             borrow of `x` occurs here
+LL |     let _y = x; //~ ERROR cannot use `x` because it was mutably borrowed
+   |              ^ use of borrowed `x`
+LL |     f;
+   |     - borrow later used here
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0503`.

src/test/ui/unboxed-closures/unboxed-closures-borrow-conflict.rs

@@ -8,13 +8,14 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// ignore-compare-mode-nll
-
 // Test that an unboxed closure that mutates a free variable will
 // cause borrow conflicts.
 
+
+
 fn main() {
     let mut x = 0;
     let f = || x += 1;
     let _y = x; //~ ERROR cannot use `x` because it was mutably borrowed
+    f;
 }