Create a build script for OpenAL Soft native binaries

[alexrp]

It looks like there's no build script for this right now. The project uses CMake, so should be fairly straightforward to integrate like all the other native projects.

[Perksey]

Please note that we generally don't use the issue tracker for non-user-facing things, these generally go on the Development Tracker here: Silk.NET Development Tracker (view) (I appreciate this is read-only to the public).

I've added this as an entry there.