qt-build-system wraps variables such as QT_PLUGIN_PATH with '= instead
of prefix, so when qtwayland is installed in a profile or included in
the environment, the application fails to see it. Programs run with
export QT_QPA_PLATFORM=wayland-egl will fail to launch.
We could:
1. Use 'prefix so that the parent environment's variables are appended
and users have to manually install qtwayland them selves.
2. Include qtwayland as an input to every qt package somehow. Can the
build system do that? Considering that Wayland seems to be the
future, I feel that Qt GUI applications should support it by
default. I mean, wayland is in the closure of qtbase anyway.
3. Both? Why is '= used anyway?
How should this be done?
