Get rid of mailbox size check.

Never seen it triggered. Furthermore, initially logging for some log
levels was asynchronous which could cause mailbox build up. But now
logging is synchronous. So mailbox lengths are linearly dependent on
the number of the processes that log something. And the latter is
entirely under user's control.
Get rid of poor man's lazy evaluation of format arguments.

It was never obvious that having this was beneficial.
Don't ignore dynamic_compile return value.
Compile generated modules synchronously.