RFR: JDK-8231974: Build fails if no common legal notices are present

[Mandy Chung]

Looks okay to me.
Mandy

On 10/8/19 12:24 PM, Erik Joelsson wrote:
> In certain Oracle build configurations, the common legal output 
> directory is never created, because there are no legal files to put in 
> it. This should not make the build fail. This patch makes adding the 
> --legal-notices parameter to jmod optional.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8231974
>
> Webrev: http://cr.openjdk.java.net/~erikj/8231974/webrev.01/
>
> /Erik
>