message: Fix `xattr.h` include path.
diff: #include <cerrno>
  #include <sys/types.h>
  -/*
  -#ifdef ELLE_LINUX
  -# include <attr/xattr.h>
  -#else
  -# include <sys/xattr.h>
  -#endif
  -*/
  -
  #include <unordered_map>
  #include <fuse/fuse.h>
  