Move context propagation and finalize_optree from do_eval to newPROG

Move context propagation and finalize_optree from do_eval to newPROG

Aborting after errors found by finalize_optree in do_eval wasn't done
properly and would cause memory problems.
This patch moves the context propagation and finalize_optree to
newPROG such that the normal error handling is done.
The eval context blk_gimme is used to communicate the context.