v.distance: relax parser rules (#2127)

* relax parser rules

* implement suggestion from code review

vector/v.distance/main.c

@@ -266,7 +266,7 @@ int main(int argc, char *argv[])
     opt.to_field->guidependency = G_store(opt.to_column->key);
 
     G_option_required(opt.out, opt.table, flag.print, opt.column, NULL);
-    G_option_exclusive(opt.out, opt.table, flag.print, NULL);
+    G_option_excludes(flag.print, opt.out, opt.table, NULL);
     G_option_requires(opt.upload, flag.print, opt.table, opt.column, NULL);
     G_option_requires(opt.column, opt.upload, NULL);
     G_option_requires(flag.print, opt.upload, NULL);