Author: James Crook <james.k.crook@gmail.com>
Date: Sun Jun 26 08:35:19 2016 +0100
Bug1223: (correction). Fix new potential crash in following pointer.
With recent changes to the Nyquist code for freeing blocks, the pointer 'next' could be uninitialised when 'list' points to the zero chain. So Audacity would follow a rogue pointer. We'd get away with it if the uninitialised value happened to be zero.