In the delete node processing: obtain the node data directly via a query
instead of a read info and upto three more functions. Retrieving the
op-depth of the interesting layers earlier avoids a lot of unneeded
guessing, which appear to cause some bugs that I intend to fix in followup
patches.

* subversion/libsvn_wc/wc-queries.sql
  (STMT_SELECT_MOVED_FOR_DELETE): Replace subquery with value.

* subversion/libsvn_wc/wc_db.c
  (delete_node): Obtain op_depth of what to delete and what to keep to avoid
    having to query for these values many times.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1567204 13f79535-47bb-0310-9956-ffa450edef68