Meta/Make: prepend the canned settings to $O

Otherwise "O=<some custom settings> Meta/Make" will not be able to
override them.
Meta/cook: notice 'I think this is ready'
Meta/RelBuild: use gpg agent

With kup, the maintainer needs to sign multiple files.  Start gpg
agent and use it for a short while.
What's cooking (2013/08 #05)