cross compile libSDL2 for macos darwin

gistfile1.txt

install zig

install libobjc

get macosX SDK from hexops.

get SDL2

mkdir build; cd build;

```
 CC="zig cc -target x86_64-macos -F /SDKs/sdk-macos-13.3/root/System/Library/Frameworks -iframework /SDKs/sdk-macos-13.3/root/System/Library/Frameworks -I /SDKs/sdk-macos-13.3/root/usr/include -fno-sanitize=undefined -Wno-nullability-completeness -Wno-undef-prefix -Wno-availability -Wno-expansion-to-defined" CXX="zig c++ -target x86_64-macos" AR="zig ar" RANLIB="zig ranlib" ../configure --host=x86_64-macos-darwin --prefix=$(pwd)/prebuilt/x86_64-macos-darwin --exec-prefix=$(pwd)/prebuilt/x86_64-macos-darwin
 make
```