fix: compilation on x86_64-swift-linux-musl

[asevko]

When building for x86_64-swift-linux-musl:

swift build --configuration release --swift-sdk x86_64-swift-linux-musl

the build failed with no such module 'Crypto' error:

warning: 'machokit': /Users/asevko/work/forks/MachOKit/Package.swift:137:1: warning: extension declares a conformance of imported type 'SwiftSetting' to imported protocol 'CaseIterable'; this will not behave correctly if the owners of 'PackageDescription' introduce this conformance in the future
135 | }
136 | 
137 | extension SwiftSetting: CaseIterable {
    | |- warning: extension declares a conformance of imported type 'SwiftSetting' to imported protocol 'CaseIterable'; this will not behave correctly if the owners of 'PackageDescription' introduce this conformance in the future
    | `- note: add '@retroactive' to silence this warning
138 |     public static var allCases: [Self] {
139 |         [
[1/1] Planning build
Building for production...
warning: '--product' cannot be used with the automatic product 'MachOKit'; building the default target instead
/Users/asevko/work/forks/MachOKit/Sources/MachOKit/Model/Codesign/CodeDirectory/CodeSignCodeDirectory.swift:16:16: error: no such module 'Crypto'
 14 | #else
 15 | #if compiler(>=6.0)
 16 | private import Crypto
    |                `- error: no such module 'Crypto'
 17 | #elseif compiler(>=5.10) && hasFeature(AccessLevelOnImport)
 18 | private import Crypto

That happens when cross-compiling on macOS to linux due to the reason, that

#if (os(macOS) || os(iOS) || os(watchOS) || os(tvOS)) &&  canImport(CommonCrypto)

evaluates on macOs, so the swift-crypto won't be added as a dependency. So we have to declare the package swift-crypto unconditionally, conditionally link the product for linux platforms.

Note: the x86_64-swift-linux-musl toolchain is installed via swiftly; the active toolchain should also be managed by swiftly >= 6.3.0 as on lower versions there was a compiler crash. For validating build on x86_64-swift-linux-musl the patch from p-x9/ObjectArchiveKit#5 is also required.

[p-x9]

Thank you for the PR.
I hadn’t considered cross-compilation.

The PR you submitted to ObjectArchiveKit has already been merged, and a new version has been released.
https://github.com/p-x9/ObjectArchiveKit/releases/tag/0.5.0

[asevko]

Should I bump ObjectArchiveKit and then update my PR to MachOKit?