CryptoBase not supported on Intel Mac

```
% swift package update
Fetching https://github.com/krzyzanowskim/CryptoSwift.git from cache
Fetching https://github.com/BlockchainCommons/secp256k1-zkp.swift.git from cache
Fetching https://github.com/WolfMcNally/WolfBase from cache
Fetched https://github.com/WolfMcNally/WolfBase (0.24s)
Fetched https://github.com/BlockchainCommons/secp256k1-zkp.swift.git (0.24s)
Fetched https://github.com/krzyzanowskim/CryptoSwift.git (0.24s)
Computing version for https://github.com/BlockchainCommons/secp256k1-zkp.swift.git
Computed https://github.com/BlockchainCommons/secp256k1-zkp.swift.git at 0.5.1 (0.49s)
Computing version for https://github.com/WolfMcNally/WolfBase
Computed https://github.com/WolfMcNally/WolfBase at 5.3.0 (0.46s)
Fetching https://github.com/apple/swift-algorithms.git from cache
Fetched https://github.com/apple/swift-algorithms.git (0.24s)
Computing version for https://github.com/apple/swift-algorithms.git
Computed https://github.com/apple/swift-algorithms.git at 1.0.0 (0.48s)
Fetching https://github.com/apple/swift-numerics from cache
Fetched https://github.com/apple/swift-numerics (0.26s)
Computing version for https://github.com/apple/swift-numerics
Computed https://github.com/apple/swift-numerics at 1.0.2 (0.49s)
Computing version for https://github.com/krzyzanowskim/CryptoSwift.git
Computed https://github.com/krzyzanowskim/CryptoSwift.git at 1.7.0 (0.48s)
Creating working copy for https://github.com/krzyzanowskim/CryptoSwift.git
Working copy of https://github.com/krzyzanowskim/CryptoSwift.git resolved at 1.7.0
Creating working copy for https://github.com/apple/swift-numerics
Working copy of https://github.com/apple/swift-numerics resolved at 1.0.2
Creating working copy for https://github.com/WolfMcNally/WolfBase
Working copy of https://github.com/WolfMcNally/WolfBase resolved at 5.3.0
Creating working copy for https://github.com/apple/swift-algorithms.git
Working copy of https://github.com/apple/swift-algorithms.git resolved at 1.0.0
Creating working copy for https://github.com/BlockchainCommons/secp256k1-zkp.swift.git
Working copy of https://github.com/BlockchainCommons/secp256k1-zkp.swift.git resolved at 0.5.1
pusateri@granite BCSwiftCrypto % swift build
Building for debugging...
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
:2:9: note: in file included from :2:
#import "Headers/CryptoBase-Swift.h"
^
/Users/pusateri/Projects/BCSwiftCrypto/.build/x86_64-apple-macosx/debug/CryptoBase.framework/Headers/CryptoBase-Swift.h:263:2: error: unsupported Swift architecture
#error unsupported Swift architecture
^
:0: error: could not build Objective-C module 'CryptoBase'
```