Merge InnoDB 5.7 from mysql-5.7.9.

Contains also

MDEV-10547: Test multi_update_innodb fails with InnoDB 5.7

	The failure happened because 5.7 has changed the signature of
	the bool handler::primary_key_is_clustered() const
	virtual function ("const" was added). InnoDB was using the old
	signature which caused the function not to be used.

MDEV-10550: Parallel replication lock waits/deadlock handling does not work with InnoDB 5.7

	Fixed mutexing problem on lock_trx_handle_wait. Note that
	rpl_parallel and rpl_optimistic_parallel tests still
	fail.

MDEV-10156 : Group commit tests fail on 10.2 InnoDB (branch bb-10.2-jan)
  Reason: incorrect merge

MDEV-10550: Parallel replication can't sync with master in InnoDB 5.7 (branch bb-10.2-jan)
  Reason: incorrect merge

mysql-test/suite/sys_vars/t/innodb_undo_tablespaces_basic.test

@@ -18,11 +18,8 @@
 
 --source include/have_innodb.inc
 
-####################################################################
-#   Display default value                                          #
-####################################################################
-SELECT @@GLOBAL.innodb_undo_tablespaces;
---echo 0 Expected
+SELECT @@GLOBAL.innodb_undo_tablespaces >= 0;
+let $undo_tablespaces=`SELECT @@GLOBAL.innodb_undo_tablespaces`;
 
 
 ####################################################################
@@ -41,9 +38,13 @@ SELECT COUNT(@@GLOBAL.innodb_undo_tablespaces);
 # Check if the value in GLOBAL table matches value in variable                 #
 ################################################################################
 
-SELECT VARIABLE_VALUE
+--disable_warnings
+--disable_query_log
+eval SELECT VARIABLE_VALUE-$undo_tablespaces DIFFERENCE
 FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES
 WHERE VARIABLE_NAME='innodb_undo_tablespaces';
+--enable_query_log
+--enable_warnings
 --echo 0 Expected