Newer versions of MSVC with /we4146 don't like putting negative sign behind a
unsigned number as https://github.com/harfbuzz/harfbuzz/pull/2069
That however have made https://crbug.com/1050424 this complain:
src/hb-ot-color-sbix-table.hh:304:28: runtime error: negation of -2147483648 cannot be represented in type 'int';
cast to an unsigned type to negate this value to itself
which apparently can be fixed using this change.
Let's see if this won't make another ubsan complain!
