Fix wall print condition in case of no wall(s).
Fix wall print condition in case of no wall(s).

(If no walls, it tried to suppress the first and last words.)

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