Hoist two more subroutines out of a big function.

* subversion/svn/conflict-callbacks.c
  (handle_tree_conflict, handle_obstructed_add): New, extracted out ...
  (svn_cl__conflict_func_interactive): ... from here.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1434925 13f79535-47bb-0310-9956-ffa450edef68