Support building/running on Apple Silicon Macs

[cubuspl42]

Although ARM support was recently added in #64, it wasn't focused on Macs or macOS. It would be great if the source code was ready to be built on modern Macs, one way or another.

[cubuspl42]

Known workaround:

One can build the game for x86-64 and launch it in the Rosetta compatibility mode.

1. Install Rosetta if you haven't already

softwareupdate --install-rosetta

2. Install x86-64 Homebrew if you haven't already

arch -x86_64 /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

Please note that it will be installed in the legacy /usr/local/ prefix, so if you already have ARM-native Homebrew installation preset in /opt/homebrew/, it shouldn't collide.

3. Install the x86-64 Homebrew dependencies

arch -x86_64 /usr/local/bin/brew install sdl2 libxmp libvorbis libogg

4. Built the game for x86-64

arch -x86_64 ./make-macosx.sh x86_64

App bundle generation will likely fail, but this is a separate issue: #69

The game binary itself should be built successfully.

4. Run the built x86-64 binary (it should automatically run in the Rosetta compatibility mode):

./build/release-darwin-x86_64/openarena.x86_64

The game will likely crash at startup, not being able to find the game data. You can solve this by putting the game data (the heavy baseoa folder) at ~/Library/Application Support/OpenArena/baseoa.

The game might crash at runtime in a strncpy call, when launching the match, but this is a separate issue: #91

This allows to run the game locally, on the machine you built it. For creating the app bundle, see #69 (comment).