Auto merge of #65708 - Mark-Simulacrum:beta-backports, r=pietroalbini

[beta] backport rollup

This includes a bunch of PRs:
 *  Fix redundant semicolon lint interaction with proc macro attributes #64387
 *  Upgrade async/await to "used" keywords. #64875
 *  syntax: fix dropping of attribute on first param of non-method assocated fn #64894
 *  async/await: improve not-send errors #64895
 *  Silence unreachable code lint from await desugaring #64930
 *  Always mark rust and rust-call abi's as unwind #65020
 *  Account for macro invocation in `let mut $pat` diagnostic. #65123
 *  Ensure that associated `async fn`s have unique fresh param names #65142
 *  Add troubleshooting section to PGO chapter in rustc book. #65402
 *  Upgrade GCC to 8.3.0, glibc to 1.17.0 and crosstool-ng to 1.24.0 for dist-armv7-linux #65302
 *  Optimize `try_expand_impl_trait_type` #65293
 *  use precalculated dominators in explain_borrow #65172
 *  Fix ICE #64964 #64989

src/ci/docker/README.md

@@ -165,18 +165,17 @@ For targets: `arm-unknown-linux-gnueabihf`
 For targets: `armv7-unknown-linux-gnueabihf`
 
 - Path and misc options > Prefix directory = /x-tools/${CT\_TARGET}
-- Path and misc options > Patches origin = Bundled, then local
-- Path and misc options > Local patch directory = /tmp/patches
+- Path and misc options > Patches origin = Bundled only
 - Target options > Target Architecture = arm
 - Target options > Suffix to the arch-part = v7
 - Target options > Architecture level = armv7-a -- (+)
 - Target options > Use specific FPU = vfpv3-d16 -- (\*)
 - Target options > Floating point = hardware (FPU) -- (\*)
 - Target options > Default instruction set mode = thumb -- (\*)
 - Operating System > Target OS = linux
-- Operating System > Linux kernel version = 3.2.72 -- Precise kernel
-- C-library > glibc version = 2.16.0
-- C compiler > gcc version = 5.2.0
+- Operating System > Linux kernel version = 3.2.101
+- C-library > glibc version = 2.17.0
+- C compiler > gcc version = 8.3.0
 - C compiler > C++ = ENABLE -- to cross compile LLVM
 
 (\*) These options have been selected to match the configuration of the arm

src/ci/docker/dist-armv7-linux/Dockerfile

@@ -3,20 +3,14 @@ FROM ubuntu:16.04
 COPY scripts/cross-apt-packages.sh /scripts/
 RUN sh /scripts/cross-apt-packages.sh
 
-# Ubuntu 16.04 (this container) ships with make 4, but something in the
-# toolchains we build below chokes on that, so go back to make 3
-COPY scripts/make3.sh /scripts/
-RUN sh /scripts/make3.sh
-
-COPY scripts/crosstool-ng.sh /scripts/
+COPY dist-armv7-linux/crosstool-ng.sh /scripts/
 RUN sh /scripts/crosstool-ng.sh
 
 COPY scripts/rustbuild-setup.sh /scripts/
 RUN sh /scripts/rustbuild-setup.sh
 USER rustbuild
 WORKDIR /tmp
 
-COPY dist-armv7-linux/patches/ /tmp/patches/
 COPY dist-armv7-linux/build-toolchains.sh dist-armv7-linux/armv7-linux-gnueabihf.config /tmp/
 RUN ./build-toolchains.sh