math.unsigned: fix put_bytes()

[tankf33der]

The two-line patch speaks for itself and test can not pass on master.

p.s. I'm not sure if I have the right(s) to include and rely on the rand module for random numbers, but it can always be redone.

[spytheman]

p.s. I'm not sure if I have the right(s) to include and rely on the rand module for random numbers, but it can always be redone.

There is no problem - you can import whatever you need in the tests; it does not affect other users of the module (each _test.v file is compiled as a separate program, independent from the rest).

[spytheman]

Excellent work.
Thank you @tankf33der .