RFR: 8329820: [Linux] Prefer EGL over GLX [v19]

[Thiago Milczarek Sayao]

> Wayland implementation will require EGL. 
> 
> EGL works with Xorg as well. The idea is to be EGL first and if it fails, fallback to GLX. A force flag `prism.es2.forceGLX=true` is available.
> 
> 
> See:
> [Switching the Linux graphics stack from GLX to EGL](https://mozillagfx.wordpress.com/2021/10/30/switching-the-linux-graphics-stack-from-glx-to-egl/)
> [Prefer EGL to GLX for the GL support on X11](https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/3540)

Thiago Milczarek Sayao has updated the pull request incrementally with two additional commits since the last revision:

 - Remove unused externs
 - Destroy DrawableInfo properly

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/1381/files
  - new: https://git.openjdk.org/jfx/pull/1381/files/099d406a..e88aa715

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1381&range=18
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1381&range=17-18

  Stats: 4 lines in 1 file changed: 1 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/1381.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1381/head:pull/1381

PR: https://git.openjdk.org/jfx/pull/1381