bug in cond in xlisp 1.4

[Mike I'll be mellow when I'm dead Meyer]

cond's return nil for cases that don't have a list following the test
expression. For instance, (cond (t)) should return t, but will return
nil if this bug exists in your version of xlisp. The fix is in the
file xlcont.c, in the function xcond; the one if statement should read

	if (val = xlevarg(&list.n_ptr)) {

instead of

	if (xlevarg(&list.n_ptr)) {

	<mike