Removed ignore-test-compare-mode-nll from hashmap-lifetimes.rs

by strengthening the test there.

src/test/ui/hashmap-lifetimes.nll.stderr

@@ -0,0 +1,13 @@
+error[E0502]: cannot borrow `my_stuff` as mutable because it is also borrowed as immutable
+  --> $DIR/hashmap-lifetimes.rs:18:5
+   |
+LL |     let mut it = my_stuff.iter();
+   |                  -------- immutable borrow occurs here
+LL |     my_stuff.insert(1, 43); //~ ERROR cannot borrow
+   |     ^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
+LL |     it;
+   |     -- borrow later used here
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0502`.

src/test/ui/hashmap-lifetimes.rs

@@ -8,12 +8,13 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// ignore-compare-mode-nll
+
 
 fn main() {
     let mut my_stuff = std::collections::HashMap::new();
     my_stuff.insert(0, 42);
 
     let mut it = my_stuff.iter();
     my_stuff.insert(1, 43); //~ ERROR cannot borrow
+    it;
 }

src/test/ui/hashmap-lifetimes.stderr

@@ -5,6 +5,7 @@ LL |     let mut it = my_stuff.iter();
    |                  -------- immutable borrow occurs here
 LL |     my_stuff.insert(1, 43); //~ ERROR cannot borrow
    |     ^^^^^^^^ mutable borrow occurs here
+LL |     it;
 LL | }
    | - immutable borrow ends here