Review Request 8240910: jmod rejects duplicate entries in --class-path jars

[Mandy Chung]

jmod tool should ignore duplicated resources from class path and emit a 
warning.  It currently ignores duplicated resources when read from a 
directory but not from JAR entries.  It's an oversight from the fix for 
JDK-8134779 [1]

http://cr.openjdk.java.net/~mchung/jdk15/webrevs/8240910/webrev.00/

This is a simple fix applying the same fix for JDK-8134779 to ignore 
duplicated entries processed from a JAR file.

Thanks
Mandy
[1] https://bugs.openjdk.java.net/browse/JDK-8134779