RFR 8158123: NPE when the annotations is used in export-to of module-info

[ShinyaYoshida]

Hi jigsaw-dev,
I've filed the issue and created the patch for it.

Please review this:

webrev:
http://cr.openjdk.java.net/~shinyafox/jigsaw/8158123/webrev/

bugs:
https://bugs.openjdk.java.net/browse/JDK-8158123

Regards,
shinyafox(Shinya Yoshida)