Use CMAKE_PROJECT_VERSION for URLs

[Holzhaus]

This replaces #3792 by using the existing MIXXX_VERSION_MAJOR and MIXXX_VERSION_MINOR compile definitions.

@daschuer I opened this PR because I'm not that good with explaining my ideas, and it's easier to grasp the idea when looking at code rather. This change is what I meant with my second point here: #3822 (comment)

[Holzhaus]

Converted to draft for further discussion, because we first need to decide how we want to deal with the git describe --dirty situation. If we want to merge #3822, this would cause a bunch of merge conflicts which is unfair to @daschuer. If necessary, I can rebase after merging the dirty flag fix PR.

[daschuer]

Thank you. This works for me.
How many files are rebuild when the version changes?
We can fix that by making a version.cpp.in or a defs_url.cpp.in that provides a set of getter functions.

[Holzhaus]

Thank you. This works for me.
How many files are rebuild when the version changes?

These files:

[ 14%] Building CXX object CMakeFiles/mixxx-lib.dir/src/control/controlobjectscript.cpp.o
[ 14%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/controller.cpp.o
[ 14%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/controllerengine.cpp.o
[ 14%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/controllerenumerator.cpp.o
[ 14%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/controllerinputmappingtablemodel.cpp.o
[ 15%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/controllermanager.cpp.o
[ 15%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/controllermappingtablemodel.cpp.o
[ 15%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/controlleroutputmappingtablemodel.cpp.o
[ 15%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/controllerpresetfilehandler.cpp.o
[ 15%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/controllerpresetinfo.cpp.o
[ 15%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/controllerpresetinfoenumerator.cpp.o
[ 15%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/dlgcontrollerlearning.cpp.o
[ 15%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/dlgprefcontroller.cpp.o
[ 15%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/dlgprefcontrollers.cpp.o
[ 16%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/midi/midicontroller.cpp.o
[ 16%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/midi/midicontrollerpreset.cpp.o
[ 16%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/midi/midicontrollerpresetfilehandler.cpp.o
[ 16%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/midi/midienumerator.cpp.o
[ 16%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/midi/midioutputhandler.cpp.o
[ 16%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/midi/portmidicontroller.cpp.o
[ 17%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/midi/portmidienumerator.cpp.o
[ 17%] Building CXX object CMakeFiles/mixxx-lib.dir/src/dialog/dlgabout.cpp.o
[ 17%] Building CXX object CMakeFiles/mixxx-lib.dir/src/mixxx.cpp.o
[ 17%] Building CXX object CMakeFiles/mixxx-lib.dir/src/musicbrainz/web/musicbrainzrecordingstask.cpp.o
[ 17%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/broadcastprofile.cpp.o
[ 17%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/broadcastsettings.cpp.o
[ 18%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/dialog/dlgprefbeats.cpp.o
[ 18%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/dialog/dlgprefdeck.cpp.o
[ 18%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/dialog/dlgprefeq.cpp.o
[ 18%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/dialog/dlgpreferencepage.cpp.o
[ 18%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/dialog/dlgpreferences.cpp.o
[ 19%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/dialog/dlgprefinterface.cpp.o
[ 19%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/dialog/dlgprefkey.cpp.o
[ 19%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/dialog/dlgpreflibrary.cpp.o
[ 19%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/dialog/dlgprefsound.cpp.o
[ 19%] Building CXX object CMakeFiles/mixxx-lib.dir/src/skin/legacyskinparser.cpp.o
[ 20%] Building CXX object CMakeFiles/mixxx-lib.dir/src/skin/skinloader.cpp.o
[ 21%] Building CXX object CMakeFiles/mixxx-lib.dir/src/util/cmdlineargs.cpp.o
[ 21%] Building CXX object CMakeFiles/mixxx-lib.dir/src/util/versionstore.cpp.o
[ 21%] Building CXX object CMakeFiles/mixxx-lib.dir/src/widget/wmainmenubar.cpp.o
[ 21%] Building CXX object CMakeFiles/mixxx-lib.dir/src/widget/wtracktableview.cpp.o
[ 21%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/dialog/dlgprefbroadcast.cpp.o
[ 21%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/dialog/dlgprefmodplug.cpp.o
[ 21%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/hid/hidcontroller.cpp.o
[ 21%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/hid/hidenumerator.cpp.o
[ 22%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/hid/hidcontrollerpreset.cpp.o
[ 22%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/hid/hidcontrollerpresetfilehandler.cpp.o
[ 22%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/bulk/bulkcontroller.cpp.o
[ 22%] Building CXX object CMakeFiles/mixxx-lib.dir/src/controllers/bulk/bulkenumerator.cpp.o
[ 22%] Building CXX object CMakeFiles/mixxx-lib.dir/src/preferences/dialog/dlgprefvinyl.cpp.o

However, we do not change the CMAKE_PROJECT_VERSION that often (we're talking about months). Therefore I consider this neglible.

We can fix that by making a version.cpp.in or a defs_url.cpp.in that provides a set of getter functions.

This would also move the URL construction into the runtime domain rather than compile time. I'm not worried about the performance impact (I'm pretty sure that's neglible), but it will mean we need some more refactoring which i'd like to avoid right now. It would also create more conflicts with #3047 (although that PR still has some issues that need to be solved).

[Holzhaus]

No idea why this displays as failed, the build works fine. Anyway, this also part of #3841.