Fixed an integral type promotion problem by adding a JAS_CAST.
Modified the jpc_tsfb_synthesize function so that it will be a noop for
an empty sequence (in order to avoid dereferencing a null pointer).
void jpc_ppxstab_destroy(jpc_ppxstab_t *tab)
{
	int i;
	for (i = 0; i < tab->numents; ++i) {
		jpc_ppxstabent_destroy(tab->ents[i]);
	}
	if (tab->ents) {
		jas_free(tab->ents);
	}
	jas_free(tab);
}

void jpc_ppxstab_destroy(jpc_ppxstab_t *tab)
{
	int i;
	for (i = 0; i < tab->numents; ++i) {
		jpc_ppxstabent_destroy(tab->ents[i]);
	}
	if (tab->ents) {
		jas_free(tab->ents);
	}
	jas_free(tab);
}
