qt5: moc invocation broken for Qt 5.2

[frank.richter@…]

Between Qt 5.1 and 5.2, the command line syntax for moc changed, breaking builds. Specifically, the -f command line argument works differently: previously, it was -f<file> where <file> could be omitted; in Qt 5.2, it's -f <file> – notice the additional space, and <file> is not optional any more. The moc invocation by the Qt5 module relied on the old behaviour as it passed -f without a filename. Furthermore, the moc input file was passed right after the -f argument. The same usage is now interpreted as the input file being the parameter to -f, and the input it expected on stdin. Since nothing is ever written into it, moc never finishes.