Allow virglrenderer clients to add hooks for VREND_DEBUG output
For the purposes of crosvm, which links virglrenderer in a subprocess with a /dev/null
stderr, it's very inconvenient to get virglrenderer debug output. A public function to allow hooking into this output so that it can be redirected as needed would help with this. This would be similar in spirit to glDebugMessageCallback
. See related chromium bug.