Rename the 'pool' argument to 'scratch_pool'.

* subversion/include/svn_client.h:
  (svn_client_list_func2_t): Rename the argument to scratch_pool.

* subversion/svn/list-cmd.c
  (print_dirent, print_dirent_xml): Rename the argument to scratch_pool.

Patch by: Vijayaguru G <vijay{_AT_}collab.net>