Add LLVM arm64 package for M1

[steveisok]

Found this to be a missing package on the M1 when building for -os iOS -arch arm64.

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Issue Details

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Found this to be a missing package on the M1 when building for -os iOS -arch arm64.

Author:	steveisok
Assignees:	directhex
Labels:	area-Infrastructure-mono
Milestone:	6.0.0

[directhex]

This was resolved in dotnet/llvm-project#99