"Wrap day" for SDL2 related libraries

Ages ago we had an idea about a "wrap day" when people would gather to create wraps for common libraries and submit them to wrapdb. Maybe we could look into doing that now that the resurrected wrapdb seems to be going on nicely.

As the first target maybe we could have all the deps needed to build a simple game with SDL using graphics and music? Basically a slightly improved version of [this project](https://github.com/jpakkane/monocoque/blob/master/meson.build). This would mean having wraps for at least the following (some already exist, listing them for completeness):

- SDL2
- SDL Mixer
- SDL Image
- libpng (+zlib), libjpg
- liblame (or some other mp3 library?)
- ogg? flac?

It should work at least for Linux using system deps and Win32 using MSVC. macOS could also work if someone volunteers to submit patches.

Start with the referenced monocoque meson.build and inspect the existing wraps in wrapdb for SDL2-related dependencies. Define the required set from the issue, including SDL2, SDL Mixer, SDL Image, image libraries, and audio libraries. Done means the needed wraps support a simple SDL game on Linux with system dependencies and on Win32 using MSVC; macOS support is optional.

Written by the indexing model from the issue text.