[Package.swift] Add SPMLLBuild target to libSwiftPM product
[Package.swift] Add SPMLLBuild target to libSwiftPM product

JGiola/swift-package-manager,sschiau/swift-package-manager,abertelrud/swift-package-manager,sschiau/swift-package-manager,sschiau/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager,JGiola/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,sschiau/swift-package-manager,apple/swift-package-manager,apple/swift-package-manager,JGiola/swift-package-manager,sschiau/swift-package-manager,JGiola/swift-package-manager,JGiola/swift-package-manager,abertelrud/swift-package-manager