Random integer generation

[Kevin Ryde]

"Sisyphus" <kalinabears@hdc.com.au> writes:
>
> randraw.c:144: GNU MP assertion failed: m2exp / (32 - 0) < ta
> abnormal program termination

Hmm.  Looks like if one is silly enough to pass an "a" which is more
than a limb smaller than m2exp, and the current value (the seed) is
small, then the product can be smaller than m2exp, tickling that
assert.

Should try to do something about that I guess, maybe just by padding
with zeros.