boost_no_com_value_init.ipp: out of bounds array access

```
$ clang++ -I../../.. -fsanitize=undefined config_test.cpp && a
boost_no_com_value_init.ipp:429:11: runtime error: index 4 out of bounds for type 'char const[4]'
boost_no_com_value_init.ipp:443:11: runtime error: index 7 out of bounds for type 'char const[7]'
```

Start by running the reported clang++ command with UBSan from the config test directory, then inspect boost_no_com_value_init.ipp around lines 429 and 443 and the calling config_test.cpp. Done means the test still passes without the reported out-of-bounds runtime errors.

Written by the indexing model from the issue text.