Change the length of the 4vecarr array.
In the execution this resizes (to grow or shrink) the underlying Common Lisp array. The logical definition is based on resize-list:
Function:
(defun resize-4vecs$a (stobjs::i 4vecarr$a) (declare (xargs :guard (4vecarr$ap 4vecarr$a))) (resize-list 4vecarr$a stobjs::i '(-1 . 0)))