ci: Move dist-aarch64-linux to an aarch64 runner

Move the dist-aarch64-linux CI job to an aarch64 runner instead of
cross-compiling it from an x86 one. This will make it possible to
perform optimisations such as LTO, PGO and BOLT later on.

src/ci/docker/host-aarch64/dist-aarch64-linux/Dockerfile

@@ -0,0 +1,50 @@
+FROM ubuntu:22.04
+
+WORKDIR /build
+
+RUN apt-get update && \
+	apt-get install -y pkg-config curl xz-utils wget unzip git make patch perl lbzip2 gcc g++ libc6-dev cmake python3 doxygen graphviz zstd libzstd-dev openssl libssl-dev
+
+ENV PATH=/rustroot/bin:$PATH
+
+WORKDIR /tmp
+COPY host-aarch64/dist-aarch64-linux/shared.sh /tmp/
+
+ENV CC=gcc CXX=g++
+
+# Build LLVM+Clang
+COPY host-aarch64/dist-aarch64-linux/build-clang.sh /tmp/
+RUN ./build-clang.sh
+ENV CC=clang CXX=clang++
+
+COPY scripts/sccache.sh /scripts/
+RUN sh /scripts/sccache.sh
+
+ENV PGO_HOST=aarch64-unknown-linux-gnu
+ENV HOSTS=aarch64-unknown-linux-gnu
+
+ENV CPATH=/usr/include/aarch64-linux-gnu/:$CPATH
+
+ENV RUST_CONFIGURE_ARGS \
+      --build=aarch64-unknown-linux-gnu \
+      --enable-full-tools \
+      --enable-profiler \
+      --enable-sanitizers \
+      --enable-compiler-docs \
+      --set target.aarch64-unknown-linux-gnu.linker=clang \
+      --set target.aarch64-unknown-linux-gnu.ar=/rustroot/bin/llvm-ar \
+      --set target.aarch64-unknown-linux-gnu.ranlib=/rustroot/bin/llvm-ranlib \
+      --set llvm.link-shared=true \
+      --set llvm.thin-lto=false \
+      --set llvm.libzstd=true \
+      --set llvm.ninja=false \
+      --set rust.debug-assertions=false \
+      --set rust.jemalloc \
+      --set rust.use-lld=true \
+      --set rust.codegen-units=1
+
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
+
+ENV CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER=clang
+ENV DIST_SRC 1
+ENV DIST_REQUIRE_ALL_TOOLS 1

src/ci/docker/host-aarch64/dist-aarch64-linux/build-clang.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+
+set -ex
+
+source shared.sh
+
+# Try to keep the LLVM version here in sync with src/ci/scripts/install-clang.sh
+LLVM=llvmorg-19.1.5
+
+mkdir llvm-project
+cd llvm-project
+
+curl -L https://github.com/llvm/llvm-project/archive/$LLVM.tar.gz | \
+  tar xzf - --strip-components=1
+
+mkdir clang-build
+cd clang-build
+
+# For whatever reason the default set of include paths for clang is different
+# than that of gcc. As a result we need to manually include our sysroot's
+# include path, /rustroot/include, to clang's default include path.
+INC="/rustroot/include:/usr/include"
+
+# We need compiler-rt for the profile runtime (used later to PGO the LLVM build)
+# but sanitizers aren't currently building. Since we don't need those, just
+# disable them. BOLT is used for optimizing LLVM.
+hide_output \
+    cmake ../llvm \
+      -DCMAKE_BUILD_TYPE=Release \
+      -DCMAKE_INSTALL_PREFIX=/rustroot \
+      -DCOMPILER_RT_BUILD_SANITIZERS=OFF \
+      -DCOMPILER_RT_BUILD_XRAY=OFF \
+      -DCOMPILER_RT_BUILD_MEMPROF=OFF \
+      -DCOMPILER_RT_BUILD_CTX_PROFILE=OFF \
+      -DLLVM_TARGETS_TO_BUILD=AArch64 \
+      -DLLVM_INCLUDE_BENCHMARKS=OFF \
+      -DLLVM_INCLUDE_TESTS=OFF \
+      -DLLVM_INCLUDE_EXAMPLES=OFF \
+      -DLLVM_ENABLE_PROJECTS="clang;lld;compiler-rt;bolt" \
+      -DC_INCLUDE_DIRS="$INC"
+
+hide_output make -j$(nproc)
+hide_output make install
+
+cd ../..
+rm -rf llvm-project

src/ci/docker/host-aarch64/dist-aarch64-linux/shared.sh

@@ -0,0 +1,16 @@
+#!/bin/sh
+hide_output() {
+  set +x
+  on_err="
+echo ERROR: An error was encountered with the build.
+cat /tmp/build.log
+exit 1
+"
+  trap "$on_err" ERR
+  bash -c "while true; do sleep 30; echo \$(date) - building ...; done" &
+  PING_LOOP_PID=$!
+  "$@" &> /tmp/build.log
+  trap - ERR
+  kill $PING_LOOP_PID
+  set -x
+}

src/ci/github-actions/jobs.yml

@@ -128,17 +128,17 @@ auto:
   - image: aarch64-gnu-debug
     <<: *job-aarch64-linux
 
+  - image: dist-aarch64-linux
+    env:
+      CODEGEN_BACKENDS: llvm,cranelift
+    <<: *job-aarch64-linux
+
   - image: arm-android
     <<: *job-linux-4c
 
   - image: armhf-gnu
     <<: *job-linux-4c
 
-  - image: dist-aarch64-linux
-    env:
-      CODEGEN_BACKENDS: llvm,cranelift
-    <<: *job-linux-4c
-
   - image: dist-android
     <<: *job-linux-4c