Auto merge of #58413 - Centril:rollup, r=Centril

Rollup of 13 pull requests

Successful merges:

 - #57693 (Doc rewording)
 - #57815 (Speed up the fast path for assert_eq! and assert_ne!)
 - #58034 (Stabilize the time_checked_add feature)
 - #58057 (Stabilize linker-plugin based LTO (aka cross-language LTO))
 - #58137 (Cleanup: rename node_id_to_type(_opt))
 - #58166 (allow shorthand syntax for deprecation reason)
 - #58196 (Add specific feature gate error for const-unstable features)
 - #58200 (fix str mutating through a ptr derived from &self)
 - #58273 (Rename rustc_errors dependency in rust 2018 crates)
 - #58289 (impl iter() for dyn Error)
 - #58387 (Disallow `auto` trait alias syntax)
 - #58404 (use Ubuntu keyserver for CloudABI ports)
 - #58405 (Remove some dead code from libcore)

Failed merges:

r? @ghost

Author: bors

src/ci/docker/dist-various-2/build-cloudabi-toolchain.sh

@@ -32,9 +32,8 @@ ln -s ../lib/llvm-5.0/bin/lld /usr/bin/${target}-ld
 ln -s ../../${target} /usr/lib/llvm-5.0/${target}
 
 # Install the C++ runtime libraries from CloudABI Ports.
-echo deb https://nuxi.nl/distfiles/cloudabi-ports/debian/ cloudabi cloudabi > \
-    /etc/apt/sources.list.d/cloudabi.list
-curl 'https://pgp.mit.edu/pks/lookup?op=get&search=0x0DA51B8531344B15' | \
-    apt-key add -
+apt-key adv --batch --yes --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 0DA51B8531344B15
+add-apt-repository -y 'deb https://nuxi.nl/distfiles/cloudabi-ports/debian/ cloudabi cloudabi'
+
 apt-get update
-apt-get install -y $(echo ${target} | sed -e s/_/-/g)-cxx-runtime
+apt-get install -y "${target//_/-}-cxx-runtime"

src/doc/rustc/src/SUMMARY.md

@@ -13,4 +13,5 @@
 - [Targets](targets/index.md)
     - [Built-in Targets](targets/built-in.md)
     - [Custom Targets](targets/custom.md)
-- [Contributing to `rustc`](contributing.md)
+- [Linker-plugin based LTO](linker-plugin-lto.md)
+- [Contributing to `rustc`](contributing.md)