[mythtv] OpenGL: MythRenderOpenGL is not a valid OpenGL rendering context

[John Pilkington]

My F30 system with nVidia is running today's master, b4f457, and my el7 
system without nVidia or vaapi has been happily running 0d3bb, built 3 
days ago.   After installing today's build, also b4f457, mythtv-setup 
hangs.

-v playback doesn't give data that looks useful, so I'm reverting.

Renderer Mesa DRI Intel(R) Q33
OpenGL/ES version  1.4 Mesa 18.3.4

{{{
2020-01-28 17:42:11.273625 C  OpenGL: Failed to create OpenGLContext!
2020-01-28 17:42:11.273641 E  OpenGL: MythRenderOpenGL is not a valid 
OpenGL rendering context
2020-01-28 17:42:11.273647 W  OpenGL painter not recommended with this 
system's hardware/drivers. Falling back to Qt painter.
2020-01-28 17:42:11.273655 I  OpenGL: MythRenderOpenGL closing
2020-01-28 17:42:11.273670 W  OpenGL: Context about to be destroyed
}}}

John