#4689 limit of a spherical_bessel_j function

[Barton Willis]

Wrong:

(%i9) xxx : spherical_bessel_j(1,x)^2;
(%o9) (sin(x)/x-cos(x))^2/x^2
(%i10) limit(xxx,x,inf);
sign: sign of ind is undefined.
 -- an error. To debug this try: debugmode(true);

Correct, but the call to expand shouldn't be needed:

(%i11) limit(expand(xxx),x,inf);
(%o11) 0

For this particular limit, the function get-limit (defined in defint) does changes a limit at zero. There is nothing wrong with this, but we should fix limit and remove this fix in get-limit.