[base] Avoid unnecessary long division. This applies to `FT_MulDiv' but not to `FT_DivFix', where overflows or lack thereof are predicted accurately. * src/base/ftcalc.c (ft_div64by32): Improve readability. (FT_MulDiv, FT_MulDiv_No_Round) [!FT_LONG64]: Use straight division when multiplication stayed within 32 bits.