Pkgconfig flags need to inherit + add more, not overwrite
Pkgconfig flags need to inherit + add more, not overwrite

abertelrud/swift-package-manager,apple/swift-package-manager,sschiau/swift-package-manager,JGiola/swift-package-manager,vmanot/swift-package-manager,haskellswift/swift-package-manager,abertelrud/swift-package-manager,sschiau/swift-package-manager,abertelrud/swift-package-manager,vmanot/swift-package-manager,abertelrud/swift-package-manager,JGiola/swift-package-manager,vmanot/swift-package-manager,mxcl/swift-package-manager,vmanot/swift-package-manager,haskellswift/swift-package-manager,JGiola/swift-package-manager,sschiau/swift-package-manager,JGiola/swift-package-manager,mxcl/swift-package-manager,haskellswift/swift-package-manager,apple/swift-package-manager,mxcl/swift-package-manager,apple/swift-package-manager,haskellswift/swift-package-manager,apple/swift-package-manager,sschiau/swift-package-manager,mxcl/swift-package-manager,apple/swift-package-manager,JGiola/swift-package-manager,abertelrud/swift-package-manager,vmanot/swift-package-manager,sschiau/swift-package-manager