Initial patch for the implementation of window functions (MDEV-6115):

- All parsing problems look like resolved
- Stub performing name resolution of window functions
in simplest queries has been added.

sql/sql_select.cc

@@ -53,6 +53,7 @@
 #include "log_slow.h"
 #include "sql_derived.h"
 #include "sql_statistics.h"
+#include "sql_window.h"
 
 #include "debug_sync.h"          // DEBUG_SYNC
 #include <m_ctype.h>
@@ -621,6 +622,7 @@ setup_without_group(THD *thd, Ref_ptr_array ref_pointer_array,
                               COND **conds,
                               ORDER *order,
                               ORDER *group,
+                              List<Window_spec> &win_specs,
                               bool *hidden_group_fields,
                               uint *reserved)
 {
@@ -654,6 +656,8 @@ setup_without_group(THD *thd, Ref_ptr_array ref_pointer_array,
   res= res || setup_group(thd, ref_pointer_array, tables, fields, all_fields,
                           group, hidden_group_fields);
   thd->lex->allow_sum_func= save_allow_sum_func;
+  res= res || setup_windows(thd, ref_pointer_array, tables, fields, all_fields,
+                            win_specs);
   DBUG_RETURN(res);
 }
 
@@ -794,6 +798,7 @@ JOIN::prepare(TABLE_LIST *tables_init,
   if (setup_without_group(thd, ref_ptrs, tables_list,
                           select_lex->leaf_tables, fields_list,
                           all_fields, &conds, order, group_list,
+                          select_lex->window_specs,
                           &hidden_group_fields,
                           &select_lex->select_n_reserved))
     DBUG_RETURN(-1);