While this is often described as a UK/US spelling difference, the
"-ise" spelling is described as a variant by the Oxford English
Dictionary. Therefore we prefer the "-ize" spelling.
* doc/find.texi: standardize on optimize.
* find/find.1: Likewise.
* find/parser.c: Likewise.
* find/pred.c: Likewise.
* find/tree.c: Likewise.
* NEWS: Likewise (except for historical entries).