Qt RHI on the raspberry pi causes memory leaks in vc4_dri.so

Hello,

I am running my QRhi code on Raspberry Pi 4 with the GLES2 backend and open-source VC4 driver (which comes with mesa and is the only one available for AArch64).

Every call to QRhi::endFrame makes memory grow a little bit. My code works fine on all other platforms, I checked that I don't have unreleased memory issues with the vulkan validation layers and it comes out fine... I tried with both QT_QPA_PLATFORM=eglfs and xcb.

I checked a bit on the internet and found this issue from Flutter which looks similar at least in concept to what I see : https://github.com/ardera/flutter-pi/issues/133 (and the fix patch: https://github.com/ardera/flutter-pi/pull/136/commits/69f503232c16e1d57efb7fbaea3ba896dd72d234)

maybe it's entirely unrelated, but it could still be worth checking I think.