package/python-sip: remove qt4 support
python-pyqt has been removed and qt4 support is about to be dropped, so
remove the support from python-sip as well.
The comments and dependencies are not how we normally do things: the
dependency on Qt5 is obvious for a package which is essentially python
bindings for Qt5, and the other dependencies are implied by Qt5. So
remove all that and limit to a single dependency on Qt5.
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
[Arnout: further simplify dependencies and comments]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>