Selector and langmap confliction

```
./ctags --verbose -x --map-C=+.h --map-C++=-.h --c-kinds=fpvx ./libcryptsetup.h
```

Though `--map-C++=-.h` is specified, ctags chooses C++ parser for the .h file.
I'm not sure the ideal behavior but at least, C++ parser should not chosen.
