The four defaulted parameters in html_util.h stayed by-value while the
definition became const&, leaving the called overload undefined.
Linux's -shared linking hid it (lazy dlopen resolution); it broke the
book-structure HTML path at runtime. Both sides now agree (const&,
defaults kept); combine_files converted consistently as well.
(from dev a910e11431d2)
Andy Kopra
55e1a1f3ac