Fixes: Set cumulative mode to false for figuring out the executable

Task:     242513
Details:  That should fix several parsing problems for .pro files with
scopes. Enable it, see how many bug reports we get, for stuff we
accidentaly parsed correctly. Shouldn't be many. So we parse the
follwing now correctly:
unix {
    TEMP=unix
}
win32 {
    TEMP=win32
}
DESTDIR=$$TEMP