virgl/ci: Force crosvm error when exit code file is missing

crosvm-runner.sh doesn't correctly report the script execution status
if the exit code file is missing.

Fix this by returning 1 when there is no exit code available from the
script that was executed.

Fixes: 81f25d8f27 ("virgl/ci: Run each dEQP instance in its own VM")

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Reviewed-by: Rohan Garg <rohan.garg@intel.com>
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14413>

.gitlab-ci/crosvm-runner.sh

@@ -43,4 +43,5 @@ NIR_DEBUG="novalidate" LIBGL_ALWAYS_SOFTWARE="true" GALLIUM_DRIVER="$CROSVM_GALL
   -p "$CROSVM_KERNEL_ARGS" \
   /lava-files/bzImage >> $DEQP_TEMP_DIR/stderr > /dev/null
 
-exit `cat $DEQP_TEMP_DIR/exit_code`
+RET=$(cat $DEQP_TEMP_DIR/exit_code)
+exit ${RET:-1}