The variables provided by Qt 6 might just contain a relative path. This
change adds an extra function resolve these via CMAKE_PREFIX_PATH and
CMAKE_FIND_ROOT_PATH.
In Qt 5 these plugins were loaded as part of the Svg module (at least with
my patches). With Qt 6 (for which I've dropped my patches) we need to
include the plugin's config file manually.
* Making an Android APK should now generally work with NDK r21.d and
Qt 5.15.1 and CMake 3.18 although some details might still need tweaking
* It is now supposed to be used within the NDK's toolchain instead of
CMake's built-in Android support (which makes problems with newer NDK
versions)
* The old way to lookup/pass variables is preserved so it should still
work with older Qt versions and CMake's built-in Android support
* Qt's own support for invoking androiddeployqt needed to be disabled
because it lead to CMake errors (see comment)
* Only link targets using static Qt Gui/Widgets/Quick
against static plugins since currently only GUI-related
plugins are relevant
* Don't require to link explicitely against the related
module (eg. Qt Svg for the Svg icon engine) because the
imported target of the plugin should pull all required
dependencies
* Add option for linking against static Qt image format
plugins
* Link GUI applications using static Qt Gui/Widgets/Quick
against the static X11 platform integration plugin if it
is available
Martchus