dynamic_cast return 0 across modules (dynamic linking) when -fvisibility=hidden is used

**Version of emscripten/emsdk:** 3.1.15

This issue causes problems in a large project when it is ported to WASM + dynamic linking causing unexpected failures requiring debugging.
It can be fixed if __attribute__ ((visibility("default"))) is added to IInterface and CClass.

Tried --export-dynamic and it doesn't help.

[dynamic_cast_issue.zip](https://github.com/emscripten-core/emscripten/files/9396657/dynamic_cast_issue.zip)
sources are attached in archive
build.bat contains commands to build