Stabilize destructuring_assignment

Author: jhpratt

tests/ui/crashes/ice-6250.stderr

@@ -1,14 +1,3 @@
-error[E0658]: destructuring assignments are unstable
-  --> $DIR/ice-6250.rs:12:25
-   |
-LL |         Some(reference) = cache.data.get(key) {
-   |         --------------- ^
-   |         |
-   |         cannot assign to this expression
-   |
-   = note: see issue #71126 <https://github.com/rust-lang/rust/issues/71126> for more information
-   = help: add `#![feature(destructuring_assignment)]` to the crate attributes to enable
-
 error[E0601]: `main` function not found in crate `ice_6250`
   --> $DIR/ice-6250.rs:4:1
    |
@@ -41,7 +30,7 @@ error[E0308]: mismatched types
 LL |         Some(reference) = cache.data.get(key) {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `bool`, found `()`
 
-error: aborting due to 4 previous errors
+error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0308, E0601, E0658.
+Some errors have detailed explanations: E0308, E0601.
 For more information about an error, try `rustc --explain E0308`.