Bug#24568, NdbScanFilter NAND/NOR operations sometimes do not works as expected

this patch is an absolutely necessary supplement of the previous patch,
the previous patch doesnot cover isnull() and isnotnull() methods' effect.

ndb/src/ndbapi/NdbScanFilter.cpp

@@ -328,11 +328,17 @@ NdbScanFilterImpl::cond_col(Interpreter::UnaryCondition op, Uint32 AttrId){
 
 int
 NdbScanFilter::isnull(int AttrId){
+  if(m_impl.m_negative == 1)
+    return m_impl.cond_col(Interpreter::IS_NOT_NULL, AttrId);
+  else
     return m_impl.cond_col(Interpreter::IS_NULL, AttrId);
 }
 
 int
 NdbScanFilter::isnotnull(int AttrId){
+  if(m_impl.m_negative == 1)
+    return m_impl.cond_col(Interpreter::IS_NULL, AttrId);
+  else
     return m_impl.cond_col(Interpreter::IS_NOT_NULL, AttrId);
 }