MSVC warning when using iostreams as a dynamic lib

I have Iostreams 1.70 build using vcpkg as a dynamic lib, and when I use it in our project this warning shows up:

```
Warning C4275 non dll-interface class 'std::ios_base::failure' used as base for dll-interface class 'boost::iostreams::bzip2_error' wesnoth C:\Users\\Documents\vcpkg\installed\x64-windows\include\boost\iostreams\filter\bzip2.hpp 112
```