build.sh fails when building universal libs

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Upon trying to run the script, it seems to download and build SDL2, but when it gets to the universal libs part, it fails:

==> Building libSDL2 universal libs...
fatal error: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo: build/Release-iphoneos/libSDL2.a and build/Release-iphonesimulator/libSDL2.a have the same architectures (arm64) and can't be in the same fat output file

$ xcodebuild -version
Xcode 12.4
Build version 12D4e

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And I just found this article that describes why lipo is no longer going to work in Xcode 12.4: https://blog.embrace.io/xcode-12-and-xcframework/

Basically, with the new M1 CPUs, a fat binary no longer works well because two different arm64-optimized builds for two different purposes couldn't coexist. Apparently XCFramework is Apple's solution.