<AWT Dev> RFR: 8213213 : Remove src/java.desktop/unix/classes/sun/awt/X11/keysym2ucs.h

[Phil Race]

Bug: https://bugs.openjdk.java.net/browse/JDK-8213213
Webrev: http://cr.openjdk.java.net/~prr/8213213/

We have a file that is in the java source directory that is meant
to be used via an awk script + an external text database to
be turned into a Java program to (off-line from the build) generate
the file Keysym.java in this webrev.

The pain to keep it based on an uptodate X11 keysymucs.h
from the current X11 upstream sources  is far beyond the value
of having it checked in when it is not even used in the build.
So I am deleting it.
If we need to update Keysym.java we can do it manually.

-phil.