RFR [nicl] jextract: Adding long names for -t and -m. Adding tests for -t and -m

[Sundararajan Athijegannathan]

Please review 
http://cr.openjdk.java.net/~sundar/jextract_package_map/webrev.00/index.html

* Adding long names --target-package and --package-map for -t and -m
* Added tests for -t and -m options.

Thanks
-Sundar