feat: skip defeq check for synport

[digama0]

This solves the issue of ₓ in all the definitions, as well as significantly improving the performance of synport. You probably want to keep the skipDefEq option off if you are using the Mathbin compiled olean files, but for synport it's just a waste of cycles to check defeqs when we are often explicitly interested in breaking these defeqs in practice.

Fixes #170

[gebner]

You probably want to keep the skipDefEq option off if you are using the Mathbin compiled olean files

Everyone uses the default releases though, so if we enable skipDefEq then they'll have to take it.

Personally, I think we can drop import Mathbin support if this helps with the port. But I just want us to be clear that we are dropping it.