RFR 8191468: jdk.scripting.nashorn.shell (jjs) module should use optional dependency for java.compiler module

[Sundararajan Athijegannathan]

Please review.

Bug:  https://bugs.openjdk.java.net/browse/JDK-8191468
Webrev: http://cr.openjdk.java.net/~sundar/8191468/webrev.00/index.html

Thanks,
-Sundar