Rollup merge of #92274 - woppopo:const_deallocate, r=oli-obk

Add `intrinsics::const_deallocate`

Tracking issue: #79597
Related: #91884

This allows deallocation of a memory allocated by `intrinsics::const_allocate`. At the moment, this can be only used to reduce memory usage, but in the future this may be useful to detect memory leaks (If an allocated memory remains after evaluation, raise an error...?).

compiler/rustc_span/src/symbol.rs

@@ -461,6 +461,7 @@ symbols! {
         const_async_blocks,
         const_compare_raw_pointers,
         const_constructor,
+        const_deallocate,
         const_eval_limit,
         const_eval_select,
         const_eval_select_ct,