Also remove wrong ASSERT_SIZE that would trigger only when not using
flexible arrays (which was the case on win32, but not with gcc).

See discussion at:
https://bugzilla.gnome.org/show_bug.cgi?id=610183

It's not part of the standard and MSVC doesn't like it.  It makes the code
a lot less elegant than it used to be, but I think it should work now.

Thready-safety disabled in that case, until we add support for pthread, etc.
Fun...

Hiss!

Bug 592036 - integer overflow bug causes misrendering of Nepali characters

This reverts commit c939f6aff405ca7b10b1f1538f46148bff719fcb.