Ignore Layout in Unification

type:fixed

Related to issue: #1450 (closed). A regression occurs in test:

> ligo compile contract contracts/main/dex_core.ligo 

https://github.com/madfish-solutions/quipuswap-core-v2/ with lol.diff

Note: This isn't a fix for the underlying issue, but a fix to ensure no regression occurs in the 0.51.0 release.

Changelog details: Fix regression in layout unification