The name Henrik Ibsen means a lot in the theater world; what it usually does not mean is “box-office gold.” So David Ellenstein was more than a little surprised back in 2010 when his North Coast Rep production of the cerebral Norwegian playwright’s “Ghosts” became a sleeper hit. Still, says Ellenstein, that isn’t really the reason he’s returning to Ibsen now with NCRT’s first-ever staging of the masterwork “Hedda Gabler.”