Remove references to MySQL 5.7 native InnoDB partitioning

The native InnoDB partitioning was never enabled in MariaDB.
Remove some declarations and comments referring to it.

storage/innobase/handler/ha_innodb.cc

@@ -2990,7 +2990,6 @@ ha_innobase::ha_innobase(
 	TABLE_SHARE*	table_arg)
 	:handler(hton, table_arg),
 	m_prebuilt(),
-	m_prebuilt_ptr(&m_prebuilt),
 	m_user_thd(),
 	m_int_table_flags(HA_REC_NOT_IN_SEQ
 			  | HA_NULL_IN_KEY
@@ -3656,9 +3655,6 @@ innobase_init_abort()
 /** Return partitioning flags. */
 static uint innobase_partition_flags()
 {
-	/* JAN: TODO: MYSQL 5.7
-	return(HA_CAN_EXCHANGE_PARTITION | HA_CANNOT_PARTITION_FK);
-	*/
 	return (0);
 }
 
@@ -13238,8 +13234,6 @@ inline int ha_innobase::delete_table(const char* name, enum_sql_command sqlcom)
 		}
 	}
 
-	/* TODO: remove this when the conversion tool from ha_partition to
-	native innodb partitioning is completed */
 	if (err == DB_TABLE_NOT_FOUND
 	    && innobase_get_lower_case_table_names() == 1) {
 		char*	is_part = is_partition(norm_name);

storage/innobase/handler/ha_innodb.h

@@ -550,15 +550,6 @@ bool thd_is_strict_mode(const MYSQL_THD thd);
  */
 extern void mysql_bin_log_commit_pos(THD *thd, ulonglong *out_pos, const char **out_file);
 
-/** Get the partition_info working copy.
-@param	thd	Thread object.
-@return	NULL or pointer to partition_info working copy. */
-/* JAN: TODO: MySQL 5.7 Partitioning
-partition_info*
-thd_get_work_part_info(
-	THD*	thd);
-*/
-
 struct trx_t;
 #ifdef WITH_WSREP
 //extern "C" int wsrep_trx_order_before(void *thd1, void *thd2);

storage/innobase/handler/handler0alter.cc

@@ -626,14 +626,6 @@ ha_innobase::check_if_supported_inplace_alter(
 		DBUG_RETURN(HA_ALTER_INPLACE_NOT_SUPPORTED);
 	}
 
-#if 0
-	if (altered_table->file->ht != ht) {
-		/* Non-native partitioning table engine. No longer supported,
-		due to implementation of native InnoDB partitioning. */
-		DBUG_RETURN(HA_ALTER_INPLACE_NOT_SUPPORTED);
-	}
-#endif
-
 	if (!(ha_alter_info->handler_flags & ~INNOBASE_INPLACE_IGNORE)) {
 		DBUG_RETURN(HA_ALTER_INPLACE_NO_LOCK);
 	}

storage/innobase/include/ut0new.h

 /*****************************************************************************
 
 Copyright (c) 2014, 2015, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2017, 2018, MariaDB Corporation.
+Copyright (c) 2017, 2019, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -171,7 +171,6 @@ extern PSI_memory_key	mem_key_row_log_buf;
 extern PSI_memory_key	mem_key_row_merge_sort;
 extern PSI_memory_key	mem_key_std;
 extern PSI_memory_key	mem_key_trx_sys_t_rw_trx_ids;
-extern PSI_memory_key	mem_key_partitioning;
 
 /** Setup the internal objects needed for UT_NEW() to operate.
 This must be called before the first call to UT_NEW(). */

storage/innobase/ut/ut0new.cc

 /*****************************************************************************
 
 Copyright (c) 2014, 2016, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 2019, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -42,7 +43,6 @@ PSI_memory_key	mem_key_row_log_buf;
 PSI_memory_key	mem_key_row_merge_sort;
 PSI_memory_key	mem_key_std;
 PSI_memory_key	mem_key_trx_sys_t_rw_trx_ids;
-PSI_memory_key	mem_key_partitioning;
 
 #ifdef UNIV_PFS_MEMORY
 
@@ -71,7 +71,6 @@ static PSI_memory_info	pfs_info[] = {
 	{&mem_key_row_merge_sort, "row_merge_sort", 0},
 	{&mem_key_std, "std", 0},
 	{&mem_key_trx_sys_t_rw_trx_ids, "trx_sys_t::rw_trx_ids", 0},
-	{&mem_key_partitioning, "partitioning", 0},
 };
 
 /** Map used for default performance schema keys, based on file name of the