Factor out tests for WC entry present locally.

[Julian Foad <ju...@btopenworld.com>]

How's this patch?  Are the name and description of the function good?

Should any of the other dozen or so tests of "->absent" and/or "->deleted" in 
the WC library be using this function?  There are a few that look suspicious, 
but I'm not sure what they are trying to do exactly.

In subversion/libsvn_wc/adm_crawler.c (report_revisions):237:

       /* If the entry is 'deleted' or 'absent', make sure the server
          knows it's gone... */
       if (current_entry->deleted || current_entry->absent)
         {
           /* ...unless we're reporting everything, in which case it's already
              missing on the server.  */
           if (! report_everything)
             SVN_ERR (reporter->delete_path (report_baton, this_path, iterpool));
           continue;
         }

In subversion/libsvn_wc/adm_ops.c (tweak_entries):113:

       /* If a file, or deleted or absent dir in recursive mode, then tweak the
          entry but don't recurse. */
       if ((current_entry->kind == svn_node_file)
           || (recurse && (current_entry->deleted || current_entry->absent)))
         {
           SVN_ERR (svn_wc__tweak_entry (entries, name, ...
         }

In subversion/libsvn_wc/adm_ops.c (svn_wc__do_update_cleanup):228:

   if (entry->kind == svn_node_file
       || (entry->kind == svn_node_dir && (entry->deleted || entry->absent)))
     {
       ...do stuff...
     }

- Julian