This compares the request spec-version to the lib:Cabal's version in order to
determine whether cabal is able to properly understand the package. If it's
newer than the currently linked lib:Cabal version it's turned into a global
`FailResult` which the solver treats as desired in terms of backtracking and
error reporting.

This is related to the new spec-version forward-compat scheme (see #4899).

This is a forward-port of #4907 to the `master` branch