Re: [pcp] Archive pmLookupDesc errors (global derived metrics induced)

[Mark Goodwin <mgoodwin@xxxxxxxxxx>]

After chatting on IRC with Nathan ..

 __dminit() loads the global derived config(s), but then they're tracked 
per-context.
Derived names are checked in __dmcontext() and dropped if they resolve to an 
existing
metric name, so we can do a similar thing for derived metrics whose operand 
metric
name(s) do not (all) exist. Operands can't be derived, no nesting, so this 
should
be reasonably straight forward.

-- Mark