This commit handles the new engine.
* include/freetype/internal/ftcalc.h (OVERFLOW_ADD_INT32,
OVERFLOW_SUB_INT32, OVERFLOW_MUL_INT32, NEG_INT, NEG_LONG,
NEG_INT32): New macros.
* src/cff/cf2ft.c (cf2_getScaleAndHintFlag): Use OVERFLOW_ADD_INT32.
* src/cff/cf2hints.c (cf2_getWindingMomentum, cf2_hint_init,
cf2_hintmap_map, cf2_glyphpath_hintPoint,
cf2_glyphpath_computeIntersection, cf2_glyphpath_computeOffset,
cf2_glyphpath_lineTo, cf2_glyphpath_curveTo): Use
OVERFLOW_ADD_INT32, OVERFLOW_SUB_INT32, OVERFLOW_MUL_INT32, and
NEG_INT32 where appropriate.
* src/cff/cf2intrp.c (cf2_doFlex, cf2_doBlend,
cf2_interpT2CharString): Ditto.
Also add some other code where needed to avoid overflow.
e66d7300fe