pp_knowledge.c: Add filename to warnings/errors
pp_knowledge.c: Add filename to warnings/errors

Now that we have in link-parser variable-settings before the dictionary
opening, we get this on "link-parser -v2":

PP warning: Link set LEFT_DOMAIN_STARTER_LINKS not defined: assuming empty.
PP warning: Link set URFL_DOMAIN_STARTER_LINKS not defined: assuming empty.
PP warning: Link set MUST_FORM_A_CYCLE_LINKS not defined: assuming empty.
PP warning: Not using any 'form a cycle' rules
PP warning: Not using any 'bounded' rules
PP warning: Not using any CONTAINS_ONE_RULES rules
PP warning: Not using any CONTAINS_NONE_RULES rules

Note that they don't show the filename, even though it already exists
in pp_knowledge_s.

Add it.

linas/link-grammar,opencog/link-grammar,ampli/link-grammar,linas/link-grammar,ampli/link-grammar,opencog/link-grammar,ampli/link-grammar,linas/link-grammar,linas/link-grammar,linas/link-grammar,linas/link-grammar,ampli/link-grammar,opencog/link-grammar,ampli/link-grammar,opencog/link-grammar,ampli/link-grammar,opencog/link-grammar,opencog/link-grammar,linas/link-grammar,linas/link-grammar,ampli/link-grammar,opencog/link-grammar,opencog/link-grammar,opencog/link-grammar,ampli/link-grammar,ampli/link-grammar,linas/link-grammar