GitLab

Update the CI build environment to install doxygen and graphviz. Deploy the
generated documentation as pages.
Signed-off-by: Aaron Plattner <aplattner@nvidia.com>

This builds libvdpau and runs the tests, although the only test at the moment is
dlclose and it is skipped because there is no X server running in the Docker
environment.
Signed-off-by: Aaron Plattner <aplattner@nvidia.com>