[8u-dev]: request for approval: 8034179: Clean up nio genConstants

[Erik Joelsson]

I'd like to get approval for backporting this change from JDK 9. It will 
help fix JDK-8132205. The patch applies cleanly.

Bug report: https://bugs.openjdk.java.net/browse/JDK-8034179
JDK 9 changeset: http://hg.openjdk.java.net/jdk9/dev/jdk/rev/88fb01f57ffa
JDK 9 review: 
http://mail.openjdk.java.net/pipermail/build-dev/2014-February/011821.html

/Erik