[RFC] WIP: opengl interop: Implement export and import through EGL and dmabuf
This is a prototype for exporting and importing openGL texture using EGL and dmabuf fds.
- export: create an EGLImage from the texture, and export it as a dmabuf fd
- import: create an EGLImage from the fd, and use it to create the texture
A rudimentary test case for opengl (in src/tests/opengl_surfaceless.c) is also implemented.
If the import handle is set, the params->initial_data in gl_tex_create is currently ignored. I am not sure this is the desired behavior.