ci: Allow to override the virglrenderer render server

Allows this script to be used in virglrenderer CI with the actual server from
virglrenderer built from top of tree.

Signed-off-by: Corentin Noël <corentin.noel@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29158>

.gitlab-ci/crosvm-runner.sh

@@ -98,7 +98,7 @@ LIBGL_ALWAYS_SOFTWARE=${CROSVM_LIBGL_ALWAYS_SOFTWARE} \
 GALLIUM_DRIVER=${CROSVM_GALLIUM_DRIVER} \
 VK_DRIVER_FILES=$CI_PROJECT_DIR/install/share/vulkan/icd.d/${CROSVM_VK_DRIVER}_icd.x86_64.json \
 crosvm --no-syslog run \
-    --gpu "${CROSVM_GPU_ARGS}" --gpu-render-server "path=/usr/local/libexec/virgl_render_server" \
+    --gpu "${CROSVM_GPU_ARGS}" --gpu-render-server "path=${VIRGL_RENDER_SERVER:-/usr/local/libexec/virgl_render_server}" \
     -m "${CROSVM_MEMORY:-4096}" -c "${CROSVM_CPU:-2}" --disable-sandbox \
     --shared-dir /:my_root:type=fs:writeback=true:timeout=60:cache=always \
     --net "host-ip=192.168.30.1,netmask=255.255.255.0,mac=AA:BB:CC:00:00:12" \