Rollup merge of rust-lang#90550 - ehuss:update-ca, r=Mark-Simulacrum

Update certificates in some Ubuntu 16 images.

These images use crosstool-ng, which needs to download various things off the internet. The certificate for `www.kernel.org` no longer works with the ca-certificates in Ubuntu 16. This resolves the issue by grabbing from a newer image a certificate bundle from https://curl.se/ca/cacert.pem, which is usually somewhat up to date.

src/ci/docker/host-x86_64/dist-aarch64-linux/Dockerfile

@@ -1,5 +1,18 @@
+FROM ubuntu:20.04
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+        curl \
+        ca-certificates
+WORKDIR /tmp
+RUN curl -f https://curl.se/ca/cacert.pem -o cacert.pem
+
 FROM ubuntu:16.04
 
+# The ca-certificates in ubuntu-16 is too old, so update the certificates
+# with something more recent.
+COPY --from=0 /tmp/cacert.pem /tmp/cacert.pem
+ENV CURL_CA_BUNDLE /tmp/cacert.pem
+
 COPY scripts/cross-apt-packages.sh /scripts/
 RUN sh /scripts/cross-apt-packages.sh
 

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

@@ -1,5 +1,18 @@
+FROM ubuntu:20.04
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+        curl \
+        ca-certificates
+WORKDIR /tmp
+RUN curl -f https://curl.se/ca/cacert.pem -o cacert.pem
+
 FROM ubuntu:16.04
 
+# The ca-certificates in ubuntu-16 is too old, so update the certificates
+# with something more recent.
+COPY --from=0 /tmp/cacert.pem /tmp/cacert.pem
+ENV CURL_CA_BUNDLE /tmp/cacert.pem
+
 COPY scripts/cross-apt-packages.sh /scripts/
 RUN sh /scripts/cross-apt-packages.sh
 

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

@@ -1,5 +1,18 @@
+FROM ubuntu:20.04
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+        curl \
+        ca-certificates
+WORKDIR /tmp
+RUN curl -f https://curl.se/ca/cacert.pem -o cacert.pem
+
 FROM ubuntu:16.04
 
+# The ca-certificates in ubuntu-16 is too old, so update the certificates
+# with something more recent.
+COPY --from=0 /tmp/cacert.pem /tmp/cacert.pem
+ENV CURL_CA_BUNDLE /tmp/cacert.pem
+
 COPY scripts/cross-apt-packages.sh /scripts/
 RUN sh /scripts/cross-apt-packages.sh
 

src/ci/docker/host-x86_64/dist-armv7-linux/Dockerfile

@@ -1,5 +1,18 @@
+FROM ubuntu:20.04
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+        curl \
+        ca-certificates
+WORKDIR /tmp
+RUN curl -f https://curl.se/ca/cacert.pem -o cacert.pem
+
 FROM ubuntu:16.04
 
+# The ca-certificates in ubuntu-16 is too old, so update the certificates
+# with something more recent.
+COPY --from=0 /tmp/cacert.pem /tmp/cacert.pem
+ENV CURL_CA_BUNDLE /tmp/cacert.pem
+
 COPY scripts/cross-apt-packages.sh /scripts/
 RUN sh /scripts/cross-apt-packages.sh