Stabilize cfg_target_has_atomic

Closes rust-lang#32976

Author: Amanieu

alloc/src/lib.rs

@@ -140,7 +140,7 @@
 #![feature(associated_type_bounds)]
 #![feature(box_syntax)]
 #![feature(cfg_sanitize)]
-#![feature(cfg_target_has_atomic)]
+#![cfg_attr(bootstrap, feature(cfg_target_has_atomic))]
 #![feature(const_deref)]
 #![feature(const_fn_trait_bound)]
 #![feature(const_mut_refs)]

core/src/lib.rs

@@ -155,7 +155,8 @@
 #![feature(allow_internal_unstable)]
 #![feature(associated_type_bounds)]
 #![feature(auto_traits)]
-#![feature(cfg_target_has_atomic)]
+#![cfg_attr(bootstrap, feature(cfg_target_has_atomic))]
+#![cfg_attr(not(bootstrap), feature(cfg_target_has_atomic_equal_alignment))]
 #![feature(const_fn_floating_point_arithmetic)]
 #![feature(const_fn_fn_ptr_basics)]
 #![feature(const_fn_trait_bound)]

core/tests/lib.rs

@@ -7,7 +7,7 @@
 #![feature(box_syntax)]
 #![feature(cell_update)]
 #![feature(cfg_panic)]
-#![feature(cfg_target_has_atomic)]
+#![cfg_attr(bootstrap, feature(cfg_target_has_atomic))]
 #![feature(const_assume)]
 #![feature(const_black_box)]
 #![feature(const_bool_to_option)]

std/src/lib.rs

@@ -242,7 +242,7 @@
 #![feature(c_variadic)]
 #![feature(cfg_accessible)]
 #![feature(cfg_eval)]
-#![feature(cfg_target_has_atomic)]
+#![cfg_attr(bootstrap, feature(cfg_target_has_atomic))]
 #![feature(cfg_target_thread_local)]
 #![feature(char_error_internals)]
 #![feature(char_internals)]