Change options to be an unsigned integer instead of casting to one

[AZero13]

The function that takes options expects an unsigned integer, so marking options as such is a safe bet

[michaelrsweet]

Need to look at this more closely, but given that only 3 bits are currently used this change is unnecessary.

[AZero13]

It is best for portability though. Especially when the C standard guarantees bitwise operations on unsigned integers to have the expected behavior.

[AZero13]

Technically, conversion between int and unsigned int can be undefined, even if it won't happen here.