build on macOS: homebrew leveldb does not have rtti

[maparent]

I tried to install from source on MacOS (latest Big Sur, Intel) and had an issue when loading the plyvel .so, complaining about not finding the typeinfo in leveldb. It turns out the brew leveldb does not have typeinfo. Rebuilding plyvel with CFLAGS=-no-rtti solved the problem. Leaving this as reference for anybody running into the same issue, not sure if there's an action to take at the level of graphbrain.

[telmomenezes]

Thanks a lot Marc-Antoine!
I will soon add a troubleshooting section to the docs and include this tip. Are you ok if we cite you one this?