sonic-visualiser: update to 4.0

[newbluemoon]

No description provided.

[newbluemoon]

Cross-builds only seem to find the qt5 host libraries now so as a quick workaround until something better comes up I just inserted the cross base via sed into the qmake-generated makefiles.

And because the libevent update doesn’t seem to have made it to most cross targets, yet (except for armv6l-musl) I think it’d be better to wait for them to catch up and test this before merging.

[newbluemoon]

The problem with sonic-visualiser is that it is a mixed build-style: gnu-configure runs qmake in the end so that in cross cases qmake isn’t set up properly. To work-around this I just copied the creation of the qt.conf file from the qmake build-style and made qmake use it.

The xlint error is because of creating the custom qt.conf. Everything else is fine now. Tested on x86_64, x86_64-musl, and armv7l-musl (RPi).

But I think there are some other templates which are mixed qmake build-styles. Would it make sense to create a qmake-cross-wrapper (but only when the build-style is not qmake) which sets up and uses a qt.conf file?

[Hoshpak]

I just stumbled upon the same issue with smplayer which uses a makefile to call qmake so I think it would be beneficial to have a build_helper or similar for that case.