Use RAII to always close display at exit.
Use RAII to always close display at exit.

The reason for doing this is that swiftshader debug libraries will
fail with an assertion error if you "leak" objects. This lets us
run with the debug libraries for more comprehensible errors.

graphicsfuzz/get-image-egl,graphicsfuzz/get-image-egl,graphicsfuzz/get-image-egl