[ruby/bigdecimal] Fix length calculation in rb_uint64_convert_to_BigDecimal
https://github.com/ruby/bigdecimal/commit/14e53ed7f6
[ruby/bigdecimal] Fix length calculation in rb_uint64_convert_to_BigDecimal
https://github.com/ruby/bigdecimal/commit/14e53ed7f6