Fixes for Mac Catalyst

[colbyn]

VIA some minor tweaks I was able to get rust to build rust-skia for the x86_64-apple-ios-macabi target. But when I link it from Xcode, Xcode complains

ld: in lib/file.a(libskia.SkPaint.o), building for Mac Catalyst, but linking in object file built for macOS, for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I don’t get what I’m doing wrong?

Rust compiled it just fine, and the underlying architecture is x86_64, but Xcode thinks that it’s built for MacOS.

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Anyway I though I’d open this WIP PR in the hope that I may get feedback of some kind that can translate to getting rust-skia building for catalyst.

[colbyn]

Theres the associated issue, which I can close.