libcCross: Use correct libSystem

Changed files
+1 -1
pkgs
top-level
+1 -1
pkgs/top-level/all-packages.nix
···
else if name == "musl" then targetPackages.muslCross or muslCross
else if name == "msvcrt" then targetPackages.windows.mingw_w64 or windows.mingw_w64
else if targetPlatform.useiOSPrebuilt then targetPackages.darwin.iosSdkPkgs.libraries
-
else if name == "libSystem" then darwin.xcode
+
else if name == "libSystem" then targetPackages.darwin.xcode
else throw "Unknown libc";
libcCross = assert targetPlatform != buildPlatform; libcCrossChooser targetPlatform.libc;