Revert "FindQt4: Don't further process qmake if it does not belong to Qt4"

This reverts commit a279641a5dbd234b45775757c1e025aa03a3281f.
The diagnostic issue was already fixed by Clinton in
83934757c942672d8bea79f11e51a184b168a212.
Merge topic 'FindQt4-ignore-qt5' into next

6112fd1a Revert "FindQt4: Don't further process qmake if it does not belong to Qt4"