https://bugs.openjdk.java.net/browse/JDK-8047931
listed a number of X11 and medialib files that are unused
in the build.
In looking at the VDrawingArea ones it lead to realising
we still include Intrinsic.h (an Xt header) in awt.h even though
we do not use Xt since the Motif toolkit was removed.
So I think we can remove the dependency on those header files.
Doing this lead in turn to finding we have at least one unused
field, one unused #define and one unused method declaration
all referencing Xt types.

So I decided to separate out the removal of Xt headers and files in to this separate bug report and make the other bug
exclusively about medialib.