Correct the `cond' forms in cl-print-string-with-limit

Correct the `cond' forms in cl-print-string-with-limit

In this function, calling with limit bound to t will cause an
error in any of the cond forms which set print-length, etc.
Correct them!

* lisp/emacs-lisp/cl-print.el (cl-print-string-with-limit):
Amend the doc string.  In the cond forms in the bindings for
print-length, etc., test the value t first.  Amend those for
print-length and print-level also to test for a zero value of
limit.