[PATCH] tests/docker: use stable URLs for zlib tarballs

The tarballs at https://zlib.net/zlib-X.Y.Z.tar.xz become unavailable
when a new release is made. This breaks the emsdk-wasm64-cross.docker
file that fetches the tarball and builds zlib from source.

There is actually an archive available with a stable URL. Use that
instead. This does require switching from xz to gzip since xz tarballs
are not available in the archive.

The upshot is that the emsdk-wasm64-cross Docker image build will
continue working into the future without causing CI breakage when the
zlib project makes a new release.

Reported-by: Michael Tokarev <[email protected]>
Suggested-by: Daniel P. Berrangé <[email protected]>
Reviewed-by: Daniel P. Berrangé <[email protected]>
Signed-off-by: Stefan Hajnoczi <[email protected]>
---
v2:
- Fix "bzip2 to gzip since bzip2" typo. It should have been xz instead
  of bzip2. [danpb]

 tests/docker/dockerfiles/emsdk-wasm64-cross.docker | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/docker/dockerfiles/emsdk-wasm64-cross.docker b/tests/docker/dockerfiles/emsdk-wasm64-cross.docker
index c04a741b0e5..4f26ce7a269 100644
--- a/tests/docker/dockerfiles/emsdk-wasm64-cross.docker
+++ b/tests/docker/dockerfiles/emsdk-wasm64-cross.docker
@@ -56,8 +56,8 @@ EOF
 FROM build-base AS zlib-dev
 ARG ZLIB_VERSION
 RUN mkdir -p /zlib
-RUN curl -Ls https://zlib.net/zlib-$ZLIB_VERSION.tar.xz | \
-    tar xJC /zlib --strip-components=1
+RUN curl -Ls https://zlib.net/fossils/zlib-$ZLIB_VERSION.tar.gz | \
+    tar xzC /zlib --strip-components=1
 WORKDIR /zlib
 RUN emconfigure ./configure --prefix=$TARGET --static
 RUN emmake make install -j$(nproc)
-- 
2.55.0