HPCC-14656 Fix windows link problem

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>

common/thorhelper/roxiehelper.cpp

@@ -30,6 +30,14 @@
 
 unsigned traceLevel = 0;
 
+const void * IEngineRowStream::nextRowGE(const void * seek, unsigned numFields, bool &wasCompleteMatch, const SmartStepExtra &stepExtra)
+{
+    // can only be called on stepping fields.
+    throwUnexpected();
+}
+
+//=========================================================================================
+
 //OwnedRowArray
 void OwnedRowArray::clear()
 {

common/thorhelper/roxiestream.hpp

@@ -26,13 +26,13 @@
 // Base classes for all Roxie/HThor/Thor input streams
 //---------------------------------------------------
 
-class SmartStepExtra;
+struct SmartStepExtra;
 
 interface THORHELPER_API IEngineRowStream : public IRowStream
 {
     virtual bool nextGroup(ConstPointerArray & group);      // note: default implementation can be overridden for efficiency...
     virtual void readAll(RtlLinkedDatasetBuilder &builder); // note: default implementation can be overridden for efficiency...
-    virtual const void *nextRowGE(const void * seek, unsigned numFields, bool &wasCompleteMatch, const SmartStepExtra &stepExtra) { throwUnexpected(); }    // can only be called on stepping fields.
+    virtual const void *nextRowGE(const void * seek, unsigned numFields, bool &wasCompleteMatch, const SmartStepExtra &stepExtra);
 };
 
 #endif // ROXIESTREAM_HPP