Rollup merge of #91355 - alexcrichton:stabilize-thread-local-const, r=m-ou-se

std: Stabilize the `thread_local_const_init` feature

This commit is intended to follow the stabilization disposition of the
FCP that has now finished in #84223. This stabilizes the ability to flag
thread local initializers as `const` expressions which enables the macro
to generate more efficient code for accessing it, notably removing
runtime checks for initialization.

More information can also be found in #84223 as well as the tests where
the feature usage was removed in this PR.

Closes #84223

src/test/codegen/auxiliary/thread_local_aux.rs

@@ -1,5 +1,4 @@
 #![crate_type = "lib"]
-#![feature(thread_local_const_init)]
 
 use std::cell::Cell;
 

src/test/codegen/thread-local.rs

@@ -6,7 +6,6 @@
 // ignore-android does not use #[thread_local]
 
 #![crate_type = "lib"]
-#![feature(thread_local_const_init)]
 
 extern crate thread_local_aux as aux;
 

src/test/ui/feature-gates/thread-local-const-init.rs

@@ -1,4 +0,0 @@
-thread_local!(static X: u32 = const { 0 });
-//~^ ERROR: use of unstable library feature 'thread_local_const_init'
-
-fn main() {}

src/test/ui/feature-gates/thread-local-const-init.stderr

@@ -1,13 +0,0 @@
-error[E0658]: use of unstable library feature 'thread_local_const_init'
-  --> $DIR/thread-local-const-init.rs:1:1
-   |
-LL | thread_local!(static X: u32 = const { 0 });
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #84223 <https://github.com/rust-lang/rust/issues/84223> for more information
-   = help: add `#![feature(thread_local_const_init)]` to the crate attributes to enable
-   = note: this error originates in the macro `$crate::__thread_local_inner` (in Nightly builds, run with -Z macro-backtrace for more info)
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0658`.