ghci: Load static objects in batches

Previously in the case where GHC was dynamically linked we would load
static objects one-by-one by linking each into its own shared object and
dlopen'ing each in order. However, this meant that the link would fail
in the event that the objects had cyclic symbol dependencies.

Here we fix this by merging each "run" of static objects into a single
shared object and loading this.

Fixes #13786 for the case where GHC is dynamically linked.