Faster _CustomWriteIntUnrolledSigned
Faster _CustomWriteIntUnrolledSigned

Tested across integers of all lengths this was between 90-95% of the
time of the original (sweet spots were at 3/6/9 which were 75%,91%,94%
and worst spot was 5 digits which was 102%). Adds buffer that is "1000 *
3 * sizeof(char)".

kevin-montrose/Jil,mgravell/Jil,buybackoff/Jil,larrynung/Jil,NickCraver/Jil,m0sa/Jil