[truetype] Mask numeric overflows.

* src/truetype/ttinterp.c (Move_CVT, Move_CVT_Stretched, Ins_MIRP):
Mask numeric overflows.

Reported as

  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=11681
  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=11734
2 files changed