Build libzstd from source because the EPEL package is built without fPIC.

Author: khuey

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

@@ -12,7 +12,6 @@ RUN sed -i /etc/yum.repos.d/*.repo -e 's!^mirrorlist!#mirrorlist!' \
 RUN sed -i 's/enabled=1/enabled=0/' /etc/yum/pluginconf.d/fastestmirror.conf
 
 RUN yum upgrade -y && \
-    yum install -y epel-release && \
     yum install -y \
       automake \
       bzip2 \
@@ -25,7 +24,6 @@ RUN yum upgrade -y && \
       libedit-devel \
       libstdc++-devel.i686 \
       libstdc++-devel.x86_64 \
-      libzstd-static.x86_64 \
       make \
       ncurses-devel \
       openssl-devel \
@@ -58,6 +56,10 @@ RUN ./build-gcc.sh && yum remove -y gcc gcc-c++
 COPY scripts/cmake.sh /tmp/
 RUN ./cmake.sh
 
+# rustc's LLVM needs zstd.
+COPY scripts/zstd.sh /tmp/
+RUN ./zstd.sh
+
 # Now build LLVM+Clang, afterwards configuring further compilations to use the
 # clang/clang++ compilers.
 COPY host-x86_64/dist-x86_64-linux/build-clang.sh /tmp/

src/ci/docker/scripts/zstd.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+set -ex
+
+hide_output() {
+  set +x
+  on_err="
+echo ERROR: An error was encountered with the build.
+cat /tmp/zstd_build.log
+exit 1
+"
+  trap "$on_err" ERR
+  bash -c "while true; do sleep 30; echo \$(date) - building ...; done" &
+  PING_LOOP_PID=$!
+  "$@" &> /tmp/zstd_build.log
+  trap - ERR
+  kill $PING_LOOP_PID
+  rm /tmp/zstd_build.log
+  set -x
+}
+
+ZSTD=1.5.6
+curl -L https://github.com/facebook/zstd/releases/download/v$ZSTD/zstd-$ZSTD.tar.gz | tar xzf -
+
+cd zstd-$ZSTD
+CFLAGS=-fPIC hide_output make -j$(nproc) VERBOSE=1
+hide_output make install
+
+cd ..
+rm -rf zstd-$ZSTD