[coreboot] libpayload: Convert HEX2BIN/BIN2HEX to functions, add abs() et al

[Segher Boessenkool]

> Do we really need all the types?  I think that we can get by
> with just abs(), and probably even make it a #define which will
> eliminate the need for type checking anyway.

Only if you are really careful and make it a statement expression...

> #define abs(_a) ((_a) >= 0 ? (_a) : -(_a))

...since this version ("the obvious version") suffers from double
evaluation.


Segher