Android - Malformed screen output on PowerVR w/ OpenGL

[SeongGino]

(Decided this was a core issue because this does not happen on virtually every other libretro core on said device)

As of current Beetle PCE and RetroArch 1.10.3, this is the output I'm finding on the device in question, running with gl video driver:

In case you couldn't tell, that's supposed to be Bomberman.
However, it outputs properly on the same device using vulkan, as such:

(Both of these screenshots are standard Android screenies, to be representative of what the user sees).

This does not effect Beetle SuperGrafx on the same device.
I've also been unable to reproduce this on a OnePlus 7 Pro--both GL/Vulkan display this core properly on that device.

The Device in question is a Retroid Pocket 2+ (Plus, not original - big difference), which uses a Unisoc T310 - essentially a cut-down 1+3-core SD845, but with a PowerVR-GE8300.

[bslenul]

To the devs: note that this issue only seem to happen when Settings > Video > Threaded Video is disabled.

[ghost]

Looks related to #69

[bslenul]

Yep, it's displaying properly for me now! Thank you for the fix 👍