Add OSX arm64 build target.

[Faless]

New "macos_arch" to specify the desired arch, and "macos_sdk_path" to override the default SDK path.

[DrMoriarty]

@Faless Hi! What about universal architecture? like this https://github.com/godotengine/godot-cpp/pull/529/files

[samsface]

@Faless This is cool. How would I deploy an arm build though seeing gdnlib only offers x32 & x64 alts for Mac OSX?

[Calinou]

@Faless This is cool. How would I deploy an arm build though seeing gdnlib only offers x32 & x64 alts for Mac OSX?

This is being tracked in godotengine/godot#48959. The workaround is to build an universal (fat) .dylib that includes both x86_64 and ARM64 libraries, then reference it in the OSX.64 library path.

[samsface]

Ok cool this worked. I was able to create a fat binary pretty easy using the CMake build: https://github.com/samsface/godot-steam-api/blob/a62734b45f0630a005891df48b10815e170e90c8/lib/godot-cpp/conanfile.py

Though then found out steam's sdk won't ever link with arm so was all for nothing in the end 😅 .