Simplify some log code.  A follow-up to r1478220.

* subversion/libsvn_client/log.c
  (resolve_wc_opt_revs,
   resolve_wc_head_revs,
   resolve_wc_date_revs): Delete.
  (convert_opt_rev_array_to_rev_range_array): Remove the RA session outputs
    and instead take an existing session as input. Resolve revision numbers
    by calling svn_client__get_revision_number() directly instead of using
    the functions mentioned above.
  (svn_client_log5): Always open an RA session before calling
    convert_opt_rev_array_to_rev_range_array(), instead of possibly opening
    a session afterwards or not depending on what that function did.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1478998 13f79535-47bb-0310-9956-ffa450edef68