Build ninja on Linux Docker CI builds

Author: Kobzol

src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile

@@ -98,6 +98,10 @@ COPY host-x86_64/dist-x86_64-linux/build-clang.sh /tmp/
 RUN ./build-clang.sh
 ENV CC=clang CXX=clang++
 
+# Build Ninja for faster LLVM builds.
+COPY host-x86_64/dist-x86_64-linux/build-ninja.sh /tmp/
+RUN ./build-ninja.sh
+
 # rustc-perf version from 2022-04-05
 ENV PERF_COMMIT 04fccd80396f954b339c366e30221f4bd52c5e03
 RUN curl -LS -o perf.zip https://github.com/rust-lang/rustc-perf/archive/$PERF_COMMIT.zip && \

src/ci/docker/host-x86_64/dist-x86_64-linux/build-ninja.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+set -ex
+
+source shared.sh
+
+NINJA=v1.10.2
+
+mkdir ninja
+cd ninja
+
+curl -L https://github.com/ninja-build/ninja/archive/refs/tags/$NINJA.tar.gz | \
+  tar xzf - --strip-components 1
+
+mkdir ninja-build
+cd ninja-build
+
+hide_output cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/rustroot
+
+hide_output make -j$(nproc)
+hide_output make install
+
+cd ../..
+rm -rf ninja