[truetype] Integer overflows.

Reported as

  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2384
  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2391

* src/base/ftcalc.c (FT_MulDiv, FT_MulDiv_No_Round, FT_DivFix): Use
NEG_LONG.

* src/truetype/ttinterp.c (Ins_SxVTL): Use NEG_LONG.
3 files changed