Bump Cabal submodule

This requires changing the recomp007 test because now cabal passes
`this-unit-id` to executable components, and that unit-id contains a
hash which includes the ABI of the dependencies. Therefore changing the
dependencies means that -this-unit-id changes and recompilation is
triggered.

The spririt of the test is to test GHC's recompilation logic assuming
that `-this-unit-id` is constant, so we explicitly pass `-ipid` to
`./configure` rather than letting `Cabal` work it out.