[dvdplayer] Fix for timestamp correction when no audio or no video

If audio or video track is missing, we don't have to wait for the other track to have a matching timestamp jump
Also compare dts rather than correction values as suggested by FernetMenta

squash: don't update originaldts when marked as invalid
Disable textbox autoscrolling while on screensaver.
SQUASH: only if dim or black
ffmpeg: bump to 2.4
mmal: switch to thread for renderer
mmal: Protect against null pointer dereference
Revert "[dvdplayer] Fix for timestamp correction when no audio or no video"

This reverts commit 862b8c0841e8f04197c0a0815675396441a8bfbf.
Revert "[dvdplayer] Allow UpdateCorrection to handle audio and video jumping asynchronously"

This reverts commit 3aca282858cb6795502d2d3521f5b968123dd3df.
mmal: create mmal components on Configure