New implementation for 'tbclist'

- Fixes a bug, by removing dummy nodes together with the node
itself. (The previous implementation could leave dummy nodes in frames
which otherwise had no tbc variables, and therefore would not close
variables; that could leave 'tbclist' pointing higher than 'top', which
could dangle if the stack shrank.)

- Computes MAXDELTA based on the type of delta, to ease changing its
type if needed.

- Instead of 'isdummy', uses 'delta==0' to signal dummy nodes. (Dummy
nodes always have MAXDELTA for their real delta.)
2 files changed