[qaudiooutput] Resource policy for QAudioOutput.
[qaudiooutput] Only call pa_cvolme set on stream creation if volume explicitly set.

Streams without a custom volume set use suitable volume selected
by the PulseAudio server. This is usually the correct choice, since then
stream-restore module can apply old volume to the stream. Also with
Sailfish explicitly setting the volume to streams breaks system volume.
[qsoundeffect] Resource policy support for QSoundEffect.

Since sound effects are something short and mixed with other audio, do
not acquire resources explicitly. Follow the resources availability
information to determine when it is ok to play the sound effects.

When client has registered itself to resource manager, client's streams
are classified properly. If no higher priority client has acquired the
resources, isAvailable() is true, and sound effects can be played. We
do not explicitly acquire the resources, since then other clients with
the same resource class would lose the resources, thus not possible to
have second client play music with QMediaPlayer class while our client
would just want to play simple sound effects.
[qsoundeffect] Set volume only if volume was explicitly set.
[qgstreamerplayercontrol] Add resource release timer when pausing or stopping media.

If media is paused, stopped, or end of media, if state hasn't changed to
playing state, release the resources. The idea with the timer is that if
for example media player is playing one song which ends, there won't be
release()/acquire() unnecessarily if next song is immediately set as
media and started playing.
[rpm] Enable NEMO_AUDIO