Fix warning and error when compiling on Windows.

sql/item_sum.cc:
  Cast byte* to char* for creating String
sql/field.cc:
  Add missing parameter for logging warning

sql/field.cc

@@ -5573,7 +5573,7 @@ int Field_datetime::store(longlong nr)
   {
     set_datetime_warning(MYSQL_ERROR::WARN_LEVEL_WARN, 
                          ER_WARN_DATA_OUT_OF_RANGE, 
-                         initial_nr, MYSQL_TIMESTAMP_DATE);
+                         initial_nr, MYSQL_TIMESTAMP_DATE, 1);
     error= 1;
   }
 

sql/item_sum.cc

@@ -2670,7 +2670,7 @@ int dump_leaf_key(byte* key, element_count count __attribute__((unused)),
 {
   TABLE *table= item->table;
   char *record= (char*) table->record[0] + table->s->null_bytes;
-  String tmp(table->record[1], table->s->reclength, default_charset_info), tmp2;
+  String tmp((char *)table->record[1], table->s->reclength, default_charset_info), tmp2;
   String *result= &item->result;
   Item **arg= item->args, **arg_end= item->args + item->arg_count_field;