Review Request for 8074431: Remove native2ascii tool

[Mandy Chung]

This patch removes native2ascii command-line tool from JDK 9 as proposed 
in March [1].

Webrev at:
http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8074431/webrev.00/
Jon - A langtools test is updated to use a new Native2Ascii.java helper 
class instead.

Existing code that calls sun.tools.native2ascii.Main can copy the 
implementation or Native2Ascii.java.

thanks
Mandy
[1] 
http://mail.openjdk.java.net/pipermail/core-libs-dev/2015-March/032634.html