rework a bit how we manage EGL extensions

- don't advertise extensions that are not supported
  by any implementation

- remove EGL_ANDROID_swap_rectangle which is not
  implemented by anybody and confuses people

- add some comments about mandatory extensions

Bug: 5428001
Change-Id: Id8dc48116ac1d1eb79ec9ef55d03e29d4257c1f3
17 files changed
tree: 695bb20d91d01f0711fd029816af4149df759206
  1. cmds/
  2. include/
  3. libs/
  4. opengl/
  5. services/
  6. MODULE_LICENSE_APACHE2
  7. NOTICE