A recent [change](https://github.com/apple/swift-corelibs-libdispatch/pull/805) in libdispatch causes the toolchain build to fail when the minimum API level is < 28 as noted [here](https://github.com/apple/swift-corelibs-libdispatch/pull/805#issuecomment-1914122650). We need to up our API level or add a patch for libdispatch.
