Post-merge fixes:

- update ha_cassandra::start_bulk_insert() definition to match those in class handler.

storage/cassandra/ha_cassandra.cc

@@ -2033,7 +2033,7 @@ int ha_cassandra::write_row(uchar *buf)
 }
 
 
-void ha_cassandra::start_bulk_insert(ha_rows rows)
+void ha_cassandra::start_bulk_insert(ha_rows rows, uint flags)
 {
   int ires;
   if (!se && (ires= connect_and_check_options(table)))

storage/cassandra/ha_cassandra.h

@@ -208,7 +208,7 @@ public:
   virtual double read_time(uint, uint, ha_rows rows)
   { return (double) rows /  20.0+1; }
 
-  virtual void start_bulk_insert(ha_rows rows);
+  virtual void start_bulk_insert(ha_rows rows, uint flags);
   virtual int end_bulk_insert();
 
   virtual int reset();