Fix compiler warnings removing unreferenced variables

sql/field.cc:
  Removing unreferenced local variables
sql/item.cc:
  Remove unreferenced local variable
sql/sql_parse.cc:
  Remove unreferenced local variable
sql/sql_select.cc:
  Remove unreferenced local variable
sql/sql_show.cc:
  Remove unreferenced local variable

sql/field.cc

@@ -2797,7 +2797,6 @@ double Field_timestamp::val_real(void)
 
 longlong Field_timestamp::val_int(void)
 {
-  uint len,pos;
   int part_time;
   uint32 temp;
   time_t time_arg;
@@ -3926,7 +3925,6 @@ double Field_string::val_real(void)
 
 longlong Field_string::val_int(void)
 {
-  longlong value;
   CHARSET_INFO *cs=charset();
   return my_strntoll(cs,ptr,field_length,NULL,10);
 }

sql/item.cc

@@ -608,7 +608,6 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 			   (char *)field_name);
 	if (!r)
 	  return 1;
-	int res;
 	if (r->check_cols(1) || r->fix_fields(thd, tables, ref))
 	  return 1;
 	r->depended_from= last;

sql/sql_parse.cc

@@ -1461,7 +1461,6 @@ mysql_execute_command(THD *thd)
   int	res= 0;
   LEX	*lex= &thd->lex;
   TABLE_LIST *tables= (TABLE_LIST*) lex->select_lex.table_list.first;
-  TABLE_LIST *cursor;
   SELECT_LEX *select_lex= &lex->select_lex;
   SELECT_LEX_UNIT *unit= &lex->unit;
   DBUG_ENTER("mysql_execute_command");
@@ -1803,7 +1802,6 @@ mysql_execute_command(THD *thd)
       }
       if (tables->next)
       {
-	TABLE_LIST *table;
 	if (check_table_access(thd, SELECT_ACL, tables->next))
 	  goto error;				// Error message is given
       }

sql/sql_select.cc

@@ -7525,7 +7525,7 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
       JOIN_TAB *tab=join->join_tab+i;
       TABLE *table=tab->table;
       char buff[512],*buff_ptr=buff;
-      char buff1[512], buff2[512], buff3[512];
+      char buff1[512], buff2[512];
       String tmp1(buff1,sizeof(buff1),default_charset_info);
       String tmp2(buff2,sizeof(buff2),default_charset_info);
       tmp1.length(0);

sql/sql_show.cc

@@ -841,7 +841,6 @@ int
 mysqld_show_keys(THD *thd, TABLE_LIST *table_list)
 {
   TABLE *table;
-  char buff[256];
   Protocol *protocol= thd->protocol;
   DBUG_ENTER("mysqld_show_keys");
   DBUG_PRINT("enter",("db: %s  table: %s",table_list->db,
@@ -1329,7 +1328,6 @@ void mysqld_list_processes(THD *thd,const char *user, bool verbose)
   time_t now= time(0);
   while ((thd_info=thread_infos.get()))
   {
-    char buff[20],*end;
     protocol->prepare_for_resend();
     protocol->store((ulonglong) thd_info->thread_id);
     protocol->store(thd_info->user);