RX 480 with mesa git etc.

Running this gstreamer pipeline

gst-launch-1.0 -e filesrc location=big_buck_bunny_720p_1mb.mp4 ! qtdemux !
decodebin ! videoconvert ! omxh264enc ! h264parse ! matroskamux ! filesink
location=/tmp/output.mkv

works fine on 4.7.

On 4.8-rc1 running it a couple of times randomly locks up the gst-launch
process. Then while it hangs, running glxgears or so locks up everything.
On the plus side, when it works, it works a lot quicker on 4.8.

I'll look into bisecting unless someone else can reproduce and already knows
why it happens.