zig-utils: bring tests back

Fixes #99

Currently it cannot install anything, because:

First: an apt hook fails:

    E: Problem executing scripts APT::Update::Post-Invoke 'rm -f /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin || true'
    E: Sub-process returned an error code
    🚨 Error: The command exited with status 100

Second: if the hook is removed prior the `apt-get update` (`rm -f
/etc/apt/apt.conf.d/docker-clean`), we get OOM:

    dpkg: error processing archive /var/cache/apt/archives/libpython3.11-minimal_3.11.2-6_amd64.deb (--unpack):
     dpkg-deb --control subprocess returned error exit status 2
    dpkg-deb (subprocess): decompressing archive '/var/cache/apt/archives/libexpat1_2.5.0-1_amd64.deb' (size=99340) member 'control.tar': lzma error: Cannot allocate memory
    tar: This does not look like a tar archive
    tar: Exiting with failure status due to previous errors
    dpkg-deb: error: tar subprocess returned error exit status 2

... so let's just skip wine for now.

.buildkite/pipeline.yml

@@ -15,12 +15,10 @@ steps:
     command: ci/list_toolchains_platforms
   - label: "Test Release"
     command: ci/prepare_git && echo "--- ci/release" && ci/release
-  # TODO(#99) re-enable
-  # - label: "Test zig utilities"
-  #   plugins:
-  #     - docker#v5.7.0:
-  #         image: "debian:stable"
-  #   command: apt-get update && apt-get install --no-install-recommends -y wine64 python3 ca-certificates && ci/zig-utils
+  - label: "Test zig utilities"
+    command: ci/zig-utils
+    env:
+      HERMETIC_CC_TOOLCHAIN_SKIP_WINE: 1
   - label: "Test rules_cc example"
     command: ci/prepare_git && ci/test_example rules_cc override_repository
   - label: "Test bzlmod example"

ci/zig-utils

@@ -26,14 +26,18 @@ for zigfile in $(git ls-files '*.zig'); do
     done
 
 
-    echo "--- zig test $zigfile"
     # until hermetic_cc_toolchain gets a zig toolchain, run zig programs' unit tests here.
+    echo "--- zig test $zigfile"
     $ZIG test "$zigfile"
 
-    echo "--- test $zigfile via wine64"
-    $ZIG test \
-        -target x86_64-windows-gnu \
-        --test-cmd wine64-stable \
-        --test-cmd-bin \
-        "$zigfile"
+    # as of 2023-10 yours truly (@motiejus) was not able to install wine64
+    # on CI. See the commit message for details.
+    if [[ -z "${HERMETIC_CC_TOOLCHAIN_SKIP_WINE:-}" ]]; then
+        echo "--- test $zigfile via wine64"
+        $ZIG test \
+            -target x86_64-windows-gnu \
+            --test-cmd wine64-stable \
+            --test-cmd-bin \
+            "$zigfile"
+    fi
 done