gdImageScaleTwoPass memory leak fix

Fixing memory leak in gdImageScaleTwoPass, as reported by @cmb69 and
confirmed by @vapier.  This bug actually bit me in production and I'm
very thankful that it was reported with an easy fix.

Fixes #173.
static double KernelBessel_J1(const double x)
{
	double p, q;

	register long i;

	static const double
	Pone[] =
	{
		0.581199354001606143928050809e+21,
		-0.6672106568924916298020941484e+20,
		0.2316433580634002297931815435e+19,
		-0.3588817569910106050743641413e+17,
		0.2908795263834775409737601689e+15,
		-0.1322983480332126453125473247e+13,
		0.3413234182301700539091292655e+10,
		-0.4695753530642995859767162166e+7,
		0.270112271089232341485679099e+4
	},
	Qone[] =
	{
		0.11623987080032122878585294e+22,
		0.1185770712190320999837113348e+20,
		0.6092061398917521746105196863e+17,
		0.2081661221307607351240184229e+15,
		0.5243710262167649715406728642e+12,
		0.1013863514358673989967045588e+10,
		0.1501793594998585505921097578e+7,
		0.1606931573481487801970916749e+4,
		0.1e+1
	};

	p = Pone[8];
	q = Qone[8];
	for (i=7; i >= 0; i--)
	{
		p = p*x*x+Pone[i];
		q = q*x*x+Qone[i];
	}
	return (double)(p/q);
}

static double KernelBessel_J1(const double x)
{
	double p, q;

	register long i;

	static const double
	Pone[] =
	{
		0.581199354001606143928050809e+21,
		-0.6672106568924916298020941484e+20,
		0.2316433580634002297931815435e+19,
		-0.3588817569910106050743641413e+17,
		0.2908795263834775409737601689e+15,
		-0.1322983480332126453125473247e+13,
		0.3413234182301700539091292655e+10,
		-0.4695753530642995859767162166e+7,
		0.270112271089232341485679099e+4
	},
	Qone[] =
	{
		0.11623987080032122878585294e+22,
		0.1185770712190320999837113348e+20,
		0.6092061398917521746105196863e+17,
		0.2081661221307607351240184229e+15,
		0.5243710262167649715406728642e+12,
		0.1013863514358673989967045588e+10,
		0.1501793594998585505921097578e+7,
		0.1606931573481487801970916749e+4,
		0.1e+1
	};

	p = Pone[8];
	q = Qone[8];
	for (i=7; i >= 0; i--)
	{
		p = p*x*x+Pone[i];
		q = q*x*x+Qone[i];
	}
	return (double)(p/q);
}
