New review comment by Clyybber on void-packages repository

https://github.com/void-linux/void-packages/pull/27828#discussion_r555282956

Comment:
Using a dash doesn't work since `build_option_jack-session` is an invalid variable name.
This is why I initially used an if statement checking the option (because I thought it wouldn't work using an underscore), but I tested and verified that using `jack_session` works properly.