mesa: fix cross compilation (#388328)

    # libspirv2dxil itself is pretty chonky, so relocate it to its own output in

    # case anything wants to use it at some point

    "spirv2dxil"

    # tools for the host platform to be used when cross-compiling

  ] ++ lib.optionals (!needNativeCLC) [

    # tools for the host platform to be used when cross-compiling.

    # mesa builds these only when not already built. hence:

    # - for a non-cross build (needNativeCLC = false), we do not provide mesa

    #   with any `*-clc` binaries, so it builds them and installs them.

    # - for a cross build (needNativeCLC = true), we provide mesa with `*-clc`

    #   binaries, so it skips building & installing any new CLC files.

    "cross_tools"

  ];