RFR: 8236651: Simplify and update glass gtk backend

[Thiago Milczarek Sayao]

On Tue, 9 Jun 2020 23:14:31 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> I am running a full test using GTK 3 on Ubuntu 20.04 and will publish results. I will later do the same for Oracle
> Linux 7.7.
> One thing to note is that this new GTK pipeline doesn't run on Ubuntu 16.04. I get the following running any program:
> 
> ```
> $ java -Djavafx.gtk.experimental=true -Djdk.gtk.verbose=true HelloRectangle
> checking GTK version 3
> trying GTK library libgtk-3.so.0
> using GTK library version 3 set libgtk-3.so.0
> Glass GTK library to load is glassgtk3_exp
> loaded gdk_x11_display_set_window_scale
> java: symbol lookup error: /localhome/kcr/javafx/jfx-tmp/jfx/rt/build/sdk/lib/libglassgtk3_exp.so: undefined symbol:
> gdk_display_get_n_monitors ```

I have limited GTK compilation to use GTK 3.8 symbols. Will run more tests, but should fix it.

-------------

PR: https://git.openjdk.java.net/jfx/pull/77