Fix two warnings and re-enable qt5 build on systems with modern cURL

[iyesin]

Hello,

This small PR contains fixes for a problems I stepped into while trying to install craft on modern system with Qt5 as default framework.

[TheOneRing]

Hi, all of them are already fixed on master.
So if you want to backport them I recomment to do that using "git cherrypick -x id".
In addition: This is a mirror of https://invent.kde.org/packaging/craft so I'd prefer it if you could open a pull request over there.

[iyesin]

Hey @TheOneRing .
Nope, it does not fixed on master since the error is still present on LTS (Long Term Support) branch. I just tried it. The problem is still present here, on GitHub so I reported it here.