LowerTypeTests: Set small code model on imported globals.
This is either a vtable (in .data.rel.ro) or a jump table (in .text).
Either way it's expected to be in the low 2 GiB, so set the small
code model.
Reviewers: fmayer
Reviewed By: fmayer
Pull Request: https://github.com/llvm/llvm-project/pull/141324
