Don't Assign Restart Rs/Rv Unless O/G Both Active

This enables running two-phase oil/water restart cases.

ebos/eclproblem.hh

@@ -2379,8 +2379,13 @@ private:
                     this->solventSaturation_[elemIdx] = ssol;
             }
 
+            if (! this->lastRs_.empty()) {
                 this->lastRs_[elemIdx] = elemFluidState.Rs();
+            }
+
+            if (! this->lastRv_.empty()) {
                 this->lastRv_[elemIdx] = elemFluidState.Rv();
+            }
 
             if constexpr (enablePolymer)
                  this->polymerConcentration_[elemIdx] = eclWriter_->eclOutputModule().getPolymerConcentration(elemIdx);