Qt 5.15.2

[Megamouse]

This is supposed to get merged when and if we are running Qt 5.15.1 on the Docker build.
The Windows build is upgraded to QT 5.15.2

[Ghostotakoi]

Hope this fix #8409

[arabek]

FYI Qt-5.15.1 is the only available version on Gentoo as of last week.

[Cristichi]

Good luck! I'm counting on a fix to my Qt problem

[avindra]

Should be good, the Suse rpcs3 build compiles (and runs) with 5.15.1:

[AniLeo]

CI on Linux is the current blocker
QT 5.15.2 and 5.15.1 PPAs currently fail to build: https://launchpad.net/~beineri/+archive/ubuntu/opt-qt-5.15.2-xenial