[REG 5.3->5.4] [gstreamer]: There is no output when playing audio files

[REG 5.3->5.4] [gstreamer 0.10]: There is no output when playing audio files. This is a regression against Qt 5.3.2 and was introduced by 3b20608fe3a68375934aee93031ca78f87364bf4.

Qt acts as if it is playing the audio, just that no sound can be heard.