AudioCommon: Make the SoundStream global a unique_ptr

[lioncash]

Basic stuff.

Alternatively I could make the function act as a creational one and have it return a unique_ptr instance separate from the global which is then assigned to said global directly at the function usage site in Core.cpp, if preferred.

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This change is

[BhaaLseN]

Review status: 0 of 2 files reviewed at latest revision, 1 unresolved discussion.

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Source/Core/AudioCommon/AudioCommon.cpp, line 67 [r1] (raw file):

  UpdateSoundStream();

  if (!g_sound_stream->Start())

What will happen down here if g_sound_stream isn't initialized (when none of the backends was valid, and NullSound::isValid also returned false)?
It looks a little like NullSound::isValid is a tiny bit useless, in the sense of always being valid; or otherwise this piece of code down here (falling back to Null after the other backend failed to start) is rather...strange.

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Comments from Reviewable

[lioncash]

Review status: 0 of 2 files reviewed at latest revision, 1 unresolved discussion.

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Source/Core/AudioCommon/AudioCommon.cpp, line 67 [r1] (raw file):

Previously, BhaaLseN (BhaaL) wrote…

What will happen down here if g_sound_stream isn't initialized (when none of the backends was valid, and NullSound::isValid also returned false)?
It looks a little like NullSound::isValid is a tiny bit useless, in the sense of always being valid; or otherwise this piece of code down here (falling back to Null after the other backend failed to start) is rather...strange.

Yeah, it's a bit silly. I can remove the isValid check(s) if it makes sense for this PR.

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Comments from Reviewable

[delroth]

Let's fix that in a subsequent change.