* proc: flag variables correctly when range-over-func stmts are used
Argument variables of a range-over-func body closure should be returned
flagged as normal local variables, not as function arguments.
Updates #3806
* proc: for optimized functions allow .closureptr to not exist
For optimized functions .closureptr is sometimes omitted from DWARF,
allow it to be 0 and try to recover the range-over-func stack by best
effort.
Fixes#3806
