New comment by classabbyamp on void-packages repository

https://github.com/void-linux/void-packages/pull/38562#issuecomment-1210155259

Comment:
> - [Allow use of system nlohmann_json dependency](https://github.com/flightlessmango/MangoHud/commit/e1ffa0f85820abea44639438fca2152290c87ee8)

add `json-c++` to makedepends