I noticed strtoull() causes problems on some buildfarm
machines. As a fix I propose small str2num function inside
txid.c itself. Main reason is that the txid actually does
not need fully-featured strtoull (radixes, whitespace skipping).
We could include strtoull() under port/ in the future, I think
that would be good, but just for txid it is not necessary.
--
marko
