new rlm_sql connection pool logic

[Alan DeKok]

Stefan Winter wrote:
> Sounds nice! Out of curiosity: any plans to make LDAP connections
> persistent and pooled as well?

  ? They are already...

  The new connection pool code is a way to have *consistent* pools
across multiple modules.  They all share a common configuration, and
benefit from simple debugged code.

  It also means removing duplicate code in the current source, which is
always a good idea.

  Alan DeKok.