Fixed bug in get_residual when there are a large number of variables in head and/or body. Here's the comment.
/* TLS: Need to set copy_of_var_addr back to addr. Most of
the time, they will be equal, as cova was set to va.
However, var_addr might have been expanded during
load_delay_trie(). If so, then the values will be
different, and the deallocation of cova in the builtin
build_delay_lists will abort */
