Manually merge some InnoDB changes into XtraDB.
Fix ALTER TABLE bug in XtraDB with wrong comparison of row type.

mysql-test/include/varchar.inc:
  Fix in test case that which of several duplicate keys triggers an error is not
  deterministic.
mysql-test/mysql-test-run.pl:
  InnoDB does not bother to free resources individually during shutdown, but due to using
  its own memory tracking it nevertheless can free everything at exit. But XtraDB adds an
  option, on by default, to skip this extra tracking. This causes lots of Valgrind
  warnings, so needs to be disabled for Valgrind testing.
mysql-test/r/innodb.result:
  Fix in test case that which of several duplicate keys triggers an error is not
  deterministic.
mysql-test/t/innodb-use-sys-malloc.test:
  InnoDB does not bother to free resources individually during shutdown, but due to using
  its own memory tracking it nevertheless can free everything at exit. But XtraDB adds an
  option, on by default, to skip this extra tracking. This causes lots of Valgrind
  warnings, so needs to be disabled for Valgrind testing.
sql/sql_table.cc:
  Add some useful DBUG while debugging alter table.
storage/xtradb/handler/ha_innodb.cc:
  Fix that check_if_incompatible_data did not realise that ROW_TYPE_DEFAULT is identical
  to the default row format ROW_TYPE_COMPACT, causing excessive table copying in
  ALTER TABLE
  Add some useful DBUG while debugging alter table.
  Manually merge into XtraDB a few small changes for InnoDB from upstream MySQL.
storage/xtradb/include/pars0pars.h:
  Manually merge into XtraDB a few small changes for InnoDB from upstream MySQL.
storage/xtradb/include/univ.i:
  Manually merge a MariaDB fix in InnoDB into XtraDB.