Signed integer overflow is undefined behavior.
Detected with clang and -fsanitize=signed-integer-overflow
Signed-off-by: Vitaly Buka <vitalybuka@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit eca2a497)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>