* This is required because we add MAP_READ_BIT and the spec doesn't allow maps
that are both unsynchronized and reading.
* Also add a test for unsynchronised persistent maps, and update the
GL_Buffer_Updates test to not require a reference image but check each quad
individually for the expected colour.
* Built entirely independently of the main renderdoc build (for now).
* Contains python scripts & framework for running tests on a renderdoc build,
which will be run nightly.
baldurk