SDL2: Better audio support and touchscreen fixes

[WohlstandFox]

Hello!

In the past year I sent the pull-request to the SDL2 repository where I fixed the touchcreen code (it didn't worked properly at all) and implemented the support for Audio Out API which gives better stability of the sound and doesn't turn into the silence because of overloads.

https://github.com/devkitPro/SDL/pull/18

However, nobody replied about that. Could anybody review/receive this into mainstream? If any changes needed, please note about that.

[WinterMute]

I've replied on the PR. Sorry to take so long looking at it. Been yakshaving other things for a while & github seems to bury notifications sadly.

[WohlstandFox]

Done!
I made a new pull-request: https://github.com/devkitPro/SDL/pull/23 because I made a new branch in order to get rid of alien commits I pulled to me because of a lost hope you will reply soon.

[WohlstandFox]

Okay, I removed the AudioRender support as you requested. Should be fine now.