Swift 6.2 linker fails to find private symbol SwiftSyntax.SyntaxRewriter.visitationFunc depending on the number of parallel jobs

### Description The error is occurring on macOS and Linux platforms using swift 6.2 release compiler and swift-syntax 602.0.0, and the typical error message are on Linux (using the official swift:noble docker image): ``` error: link command failed with exit code 1 (use -v to see invocation) /thebug/.build/aarch64-unknown-linux-gnu/debug/CasePathsMacros-tool.build/CasePathableMacro.swift.o:CasePathableMacro.swift.o:$s15CasePathsMacros12SelfRewriterCMf:(.data+0x1358): error: undefined reference to '$s11SwiftSyntax0B8RewriterC14visitationFunc33_F0C5D882E9301122F145EADC4573BFC8LL3forAA0B0VAHcAH_tF' /thebug/.build/aarch64-unknown-linux-gnu/debug/CasePathsMacros-tool.build/CasePathableMacro.swift.o:CasePathableMacro.swift.o:$s15CasePathsMacros15ElementRewriterCMf:(.data+0x2670): error: undefined reference to '$s11SwiftSyntax0B8RewriterC14visitationFunc33_F0C5D882E9301122F145EADC4573BFC8LL3forAA0B0VAHcAH_tF' clang: error: linker command failed with exit code 1 (use -v to see invocation) [255/327] Linking CasePathsMacros-tool error: fatalError ``` on macOS 15.7.1, swiftlang-6.2.0.19.9 clang-1700.3.19.1: ``` error: link command failed with exit code 1 (use -v to see invocation) Undefined symbols for architecture arm64: "SwiftSyntax.SyntaxRewriter.(visitationFunc in _F0C5D882E9301122F145EADC4573BFC8)(for: SwiftSyntax.Syntax) -> (SwiftSyntax.Syntax) -> SwiftSyntax.Syntax", referenced from: full type metadata for CasePathsMacros.SelfRewriter in CasePathableMacro.swift.o full type metadata for CasePathsMacros.ElementRewriter in CasePathableMacro.swift.o ld: symbol(s) not found for architecture arm64 clang: error: linker command failed with exit code 1 (use -v to see invocation) [364/373] Linking CasePathsMacros-tool error: fatalError ``` We have discussed this issue with the maintainers of the https://github.com/pointfreeco/swift-case-paths repository (https://github.com/pointfreeco/swift-case-paths/issues/231) and the conclusion was this issue is occurring in the swift-syntax dependency. ### Steps to Reproduce The following appears to reliably reproduce the issue: 1) ```bash $ mkdir thebug $ cd thebug ``` add the following `Dockerfile`: ```Dockerfile FROM swift:noble WORKDIR /thebug RUN git clone --branch 1.7.2 --depth 1 https://github.com/pointfreeco/swift-case-paths . CMD ["swift", "test", "--jobs", "2"] ``` 2) run: ```bash $ docker build -t thebug . && docker run --rm thebug ``` 3) get: ``` error: link command failed with exit code 1 (use -v to see invocation) /thebug/.build/aarch64-unknown-linux-gnu/debug/CasePathsMacros-tool.build/CasePathableMacro.swift.o:CasePathableMacro.swift.o:$s15CasePathsMacros12SelfRewriterCMf:(.data+0x1358): error: undefined reference to '$s11SwiftSyntax0B8RewriterC14visitationFunc33_F0C5D882E9301122F145EADC4573BFC8LL3forAA0B0VAHcAH_tF' /thebug/.build/aarch64-unknown-linux-gnu/debug/CasePathsMacros-tool.build/CasePathableMacro.swift.o:CasePathableMacro.swift.o:$s15CasePathsMacros15ElementRewriterCMf:(.data+0x2670): error: undefined reference to '$s11SwiftSyntax0B8RewriterC14visitationFunc33_F0C5D882E9301122F145EADC4573BFC8LL3forAA0B0VAHcAH_tF' clang: error: linker command failed with exit code 1 (use -v to see invocation) [253/327] Linking CasePathsMacros-tool error: fatalError ```