Bugfix: make sure than setfrozen is harmless when simplification is off.
Bugfix: make sure than setfrozen is harmless when simplification is off.

robertsami/minisat,niklasso/minisat,niklasso/minisat,mabdula/minisat,meteor/minisat,jamesbornholt/minisat,robertsami/minisat,mabdula/minisat,meteor/minisat,jamesbornholt/minisat,meteor/minisat,mabdula/minisat,meteor/minisat