adderall.internal: Lift out the free lvar creation

Naming a free LVar should be in its own function, as we may end up using
it elsewhere too.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
adderall.internal: Minor stylistic fixups

Use - instead of _ for variable names.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>