[mythtv] Bug getting screendepth

[James Knight]

> ALSO, I can't right now even use mythtv *without* Xv, because mythtv 
> only supports 16-bit and 32-bit non-Xv mode. I should think that 
> adding support for 24bpp w/32bit pixmaps would be easy since you can 
> still use the same 32-bit pixmap-filling code, but I tried and just 
> got a messed up display. :)

So, I found that this is caused by MythTV using the 
DefaultDepthOfScreen X call on line 345 in XJ.cpp. Myth should be using 
some other call which returns the pixmap bpp, not the screen depth. At 
screen depths of 1,2,4,8,16, and 32, the two are the same, but at 
screen depth 24, the pixmap bpp can be either 24 or 32, and at depth 15 
the bpp is 16.

If the pixmap bpp is 32 but screen depth is 24, the myth non-Xv 
scaling/translation code does work (I tested by forcibly setting 
XJ_depth = 32). I don't know the X call to get the pixmap bpp, but I'm 
sure someone more knowledgeable about X can find it. :)

James