Some fixes for building with Qt 5.15 that deprecates some socket signals

[u19809]

How can these be added to the git version ?
Does this git still contain the correct sources ?

[jiakuan]

Perhaps try with a pull request?

[nathan-osman]

What signal changes? I'm looking through the list of C++ API changes for 5.15, but I don't see any signal changes for QtNetwork:

https://doc.qt.io/qt-5/sourcebreaks.html