util/error: add G_GNUC_PRINTF for various functions

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20221219130205.687815-5-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>