Merge ref '848e6746fe03' from rust-lang/rust

Pull recent changes from https://github.com/rust-lang/rust via Josh.

Upstream ref: 848e6746fe03dfd703075c5077312b63877d51d6
Filtered ref: 8a7a804
Upstream diff: rust-lang/rust@b733736...848e674

This merge was created using https://github.com/rust-lang/josh-sync.

Author: The Miri Cronjob Bot

src/lib.rs

@@ -1,4 +1,3 @@
-#![cfg_attr(bootstrap, feature(strict_overflow_ops))]
 #![feature(abort_unwind)]
 #![feature(cfg_select)]
 #![feature(rustc_private)]

tests/panic/mir-validation.rs

@@ -9,11 +9,6 @@
 // and we don't even get a regular panic; rustc aborts with a different exit code instead.
 //@ignore-host: windows
 
-// FIXME: this tests a crash in rustc. For stage1, rustc is built with the downloaded standard
-// library which doesn't yet print the thread ID. Normalization can be removed at the stage bump.
-// For the grep: cfg(bootstrap)
-//@normalize-stderr-test: "thread 'rustc' panicked" -> "thread 'rustc' ($$TID) panicked"
-
 #![feature(custom_mir, core_intrinsics)]
 use core::intrinsics::mir::*;