Add some helpers for handling transactions within wc_db.  Essentially, this takes care of the wrapping of wcroot and local_relpath, which are used in basically all wc db txns.  Use it in a couple of simple cases.
Add some helpers for handling transactions within wc_db.  Essentially, this
takes care of the wrapping of wcroot and local_relpath, which are used in
basically all wc db txns.  Use it in a couple of simple cases.

* subversion/libsvn_wc/wc_db.c
  (db_txn_callback_t, txn_baton_t, run_txn, with_db_txn): New.
  (base_remove_baton, set_changelist_baton, op_revert_baton):
    Remove.
  (db_base_remove, set_changelist_txn, op_revert_txn, op_revert_recursive_txn):
    Implement as a db_txn_callback_t.
  (svn_wc__db_base_remove, svn_wc__db_op_set_changelist, svn_wc__db_op_revert):
    Use with_db_txn() to run the txn.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion