Dav: changed COPY of a file to preserve access mask.

The behaviour is now in line with COPY of a directory with contents,
which preserves access masks on individual files, as well as the "cp"
command.

Requested by Roman Arutyunyan.

src/http/modules/ngx_http_dav_module.c

@@ -845,7 +845,7 @@ overwrite_done:
 
         cf.size = ngx_file_size(&fi);
         cf.buf_size = 0;
-        cf.access = dlcf->access;
+        cf.access = ngx_file_access(&fi);
         cf.time = ngx_file_mtime(&fi);
         cf.log = r->connection->log;