post-merge: -Werror fixes in 10.3

sql/item.h

@@ -520,7 +520,7 @@ class Rewritable_query_parameter
     Value of 0 means that this object doesn't have to be replaced
     (for example SP variables in control statements)
   */
-  uint pos_in_query;
+  my_ptrdiff_t pos_in_query;
 
   /*
     Byte length of parameter name in the statement.  This is not

storage/cassandra/ha_cassandra.cc

@@ -2360,7 +2360,7 @@ class Column_name_enumerator_impl : public Column_name_enumerator
 };
 
 
-int ha_cassandra::update_row(const uchar *old_data, uchar *new_data)
+int ha_cassandra::update_row(const uchar *old_data, const uchar *new_data)
 {
   DYNAMIC_COLUMN_VALUE *oldvals, *vals;
   LEX_STRING *oldnames, *names;

storage/cassandra/ha_cassandra.h

@@ -240,7 +240,7 @@ class ha_cassandra: public handler
   int close(void);
 
   int write_row(uchar *buf);
-  int update_row(const uchar *old_data, uchar *new_data);
+  int update_row(const uchar *old_data, const uchar *new_data);
   int delete_row(const uchar *buf);
 
   /** @brief
@@ -268,7 +268,7 @@ class ha_cassandra: public handler
   THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to,
                              enum thr_lock_type lock_type);     ///< required
 
-  my_bool register_query_cache_table(THD *thd, char *table_key,
+  my_bool register_query_cache_table(THD *thd, const char *table_key,
                                      uint key_length,
                                      qc_engine_callback
                                      *engine_callback,