CI: ssl: keep the old method for ancient OpenSSL versions

I forgot about OpenSSL 1.0.2, which neither supports the build_sw target
to build only the software, nor reliably supports parallel builds. Given
that we're building 1.0.2 and 3.0.0, let's stay on the safe side and
keep 1.x sequential.

(cherry picked from commit cbc0c232bfd02716a96639de93fe2d70242802aa)
Signed-off-by: William Lallemand <wlallemand@haproxy.org>
diff --git a/scripts/build-ssl.sh b/scripts/build-ssl.sh
index 5342dfc..1a1d04a 100755
--- a/scripts/build-ssl.sh
+++ b/scripts/build-ssl.sh
@@ -17,11 +17,17 @@
     fi
 }
 
+# recent openssl versions support parallel builds and skipping the docs,
+# while older ones require to build everything sequentially.
 build_openssl_linux () {
     (
         cd "openssl-${OPENSSL_VERSION}/"
         ./config shared --prefix="${HOME}/opt" --openssldir="${HOME}/opt" -DPURIFY
-        make -j$(nproc) build_sw
+        if [ -z "${OPENSSL_VERSION##1.*}" ]; then
+            make all
+        else
+            make -j$(nproc) build_sw
+        fi
         make install_sw
     )
 }