meson: Add a qt5 feature
This allow opting out items of the builds the depends on QT5 library. Auto-detection of QT5 in cross-build requires host tools to match with the sysroot, and detection of mis-match is not fully reliable.
This allow opting out items of the builds the depends on QT5 library. Auto-detection of QT5 in cross-build requires host tools to match with the sysroot, and detection of mis-match is not fully reliable.