Review request for JDK-8030010: cleanup native code warnings

[Mandy Chung]

This patch cleans up a few trivial native warnings (mainly remove local 
unreferenced variable)
   https://bugs.openjdk.java.net/browse/JDK-8030010
Webrev at:
http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8030010/webrev.00/

This patch was contributed by Francis Andre [1] and I fixed a couple 
other trivial ones.

Mandy
[1] 
http://mail.openjdk.java.net/pipermail/build-dev/2013-December/011332.html