Be much more careful about resizing a string argument, #'fill
2010-04-03 Aidan Kehoe <kehoea@parhasard.net>
* fns.c (Ffill):
Be much more careful about resizing a string argument, update
pointers to within the string data that may have been relocated
with the string resize. Fixes a test hang reported by Vin Shelton;
thanks, Vin.