Adjust the std library for sanitizer_cfi cfgs changes

Author: Urgau

library/std/src/lib.rs

@@ -270,6 +270,7 @@
 #![feature(allow_internal_unsafe)]
 #![feature(allow_internal_unstable)]
 #![feature(c_unwind)]
+#![feature(cfg_sanitizer_cfi)]
 #![feature(cfg_target_thread_local)]
 #![feature(cfi_encoding)]
 #![feature(concat_idents)]

library/std/src/sys/unix/thread_local_dtor.rs

@@ -11,7 +11,7 @@
 // Note, however, that we run on lots older linuxes, as well as cross
 // compiling from a newer linux to an older linux, so we also have a
 // fallback implementation to use as well.
-#[allow(unexpected_cfgs)]
+#[cfg_attr(not(bootstrap), allow(unexpected_cfgs))]
 #[cfg(any(
     target_os = "linux",
     target_os = "android",