Draft: drop MI overlay code

[metux]

[DRAFT]

None of our drivers is using it (anymore). This has been special code for supporting overlays on cards not supporting them natively (SW fallback).
Nothing announcing them anymore since almost two decades now.

The proprietary Nvidia drivers still referencing them in the symbol table, but unlikely to ever call them.
This queue is dropping them entirely to see whether the driver can still be loaded at all.

If the driver fails to load, then the next experiment will be trying what happens if we turn them into no-ops (but leaving the symbols there) --> #1787

[metux]

@ONykyf @stefan11111 @b-aaz @josephcrowell @cepelinas9000

can anybody please test this one against various Nvidia driver versions (also the older ones) ?

[cepelinas9000]

Did short test (loaded xfce session, vkgears, glxgears etc) on nvidia 470 using GTX 650 Ti - it worked fine

[metux]

Did short test (loaded xfce session, vkgears, glxgears etc) on nvidia 470 using GTX 650 Ti - it worked fine

Cool. Didn't expect that going so well.
If we can confirm this by more intensive testing, then we might really get completely rid of it (instead of turning into dummy). We probably should test things that might create an overlay, eg. some fancy video players (maybe Kodi) ?.

Did you already had a chance to test #1787 ? I wouldn't be surprised if that one's failing, because Nvidia has a tendency of dynamically looking up symbols and then taking different code pathes.

[stefan11111]

@metux We could also keep the code around but no longer export the symbols.
This way, if anyone needs this code, they can make an issue and we can easily bring it back.

And if no one reports any issues for a long enough time, we can drop it entirely.