[mythtv] render2019 comments

[John Pilkington]

I now have b449f5e running under el7 on this Core2duo Intel Q33 2.8 GHz 
box with no extra video card and a single monitor at 75 Hz.  It seems 
fine for DVB-T SD recordings.

In my earlier tests I had only tried changing the 'Current Video 
Playback Profile' and saw no change in the OSD playback_data.  Now both 
boxes have that set to Normal, and define Decoder, Max CPUs etc in the 
screens that follow it;  NVDEC (where present) and deinterlacing type 
are now shown.

On the el7 box I get this sort of report on startup and with 
mythpreviewgen and mythcommflag --rebuild.  It works, and says what it 
would like to do.  :-)

{{{

running: ionice -c3 mythpreviewgen --chanid 10001 --starttime 
20191001223800 -q
Failed to open VDPAU backend libvdpau_va_gl.so: cannot open shared 
object file: No such file or directory
libva info: VA-API version 0.40.0
libva info: va_getDriverName() returns 0
libva info: Trying to open /usr/lib64/dri/i915_drv_video.so
libva info: va_openDriver() returns -1
[AVHWDeviceContext @ 0x250ed80] Failed to initialise VAAPI connection: 
-1 (unknown libva error).
Preview created.
}}}

John P