* include/freetype/internal/ftcalc.h (ADD_INT64, SUB_INT64,
MUL_INT64, DIV_INT64) [FT_LONG64]: New macros.
* src/base/ftcalc.c (ft_corner_orientation) [FT_LONG64]: Use
`SUB_INT64' and `MUL_INT64'.
Reported as
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=10028