audio: Added SDL_PutAudioStreamDataNoCopy.

[icculus]

This allows an app to add data to an audio stream without an allocating a copy, if they are maintaining the data elsewhere.

[slouken]

I’m not sure about the name, it almost implies that since it’s const, then you’re going to make a copy of it.

[maia-s]

SDL_PutAudioStreamDataReference?

[icculus]

SDL_PutAudioStreamDataPointer? SDL_PutAudioStreamExternalData?

[maia-s]

SDL_PutAudioStreamZeroCopyData works too (tho ig it gets copied eventually?)
Maybe NoCopy instead of ZeroCopy
or DataNoCopy instead of NoCopyData

[icculus]

Renamed it to SDL_PutAudioStreamDataPointer, added a callback that fires when the buffer is totally consumed (safe to free or reuse), so you don't have to guess.

[slouken]

I'm still on the fence on the naming, but conceptually the idea is great.

[slouken]

SDL_PutAudioStreamDataPointer() makes you wonder if the other function doesn't take a pointer.
SDL_PutAudioStreamExternalData() is not bad, what about SDL_PutAudioStreamStaticData()?

[icculus]

Sam and I discussed this and we're going with SDL_PutAudioStreamDataNoCopy. We don't have (afaict) anything else in SDL that maps to the same concept; usually we'll copy data when we need it past the end of an API call, so we don't have any other naming scheme to match.

[icculus]

This is rebased with the new name, so if the builders like it and everyone is happy, we can merge it.