#9 Don't generate conflicting memory management arguments

[Ron Bodkin]

Where possible (e.g., on a Java 5 VM), detect if there
are conflicting memory management settings (e.g., on
JRockIt -Xns, on Sun VM's -XX:MaxNewSize -XX:NewSize...).

See also
http://java.sun.com/docs/hotspot/VMOptions.html for
more on Sun VM options