Added comments
Ensure that tokudb test works even if jemalloc is not installed
Removed not referenced function Item::remove_fixed()

mysql-test/suite/rpl/t/rpl_gtid_reconnect.test:
  Fixed race condition
sql/item.cc:
  Indentation fix
sql/item.h:
  Removed not used function
  Added comment
sql/sql_select.cc:
  Fixed indentation
storage/tokudb/mysql-test/rpl/include/have_tokudb.opt:
  Ensure that tokudb test works even if jemalloc is not installed
storage/tokudb/mysql-test/tokudb/suite.opt:
  Ensure that tokudb test works even if jemalloc is not installed
storage/tokudb/mysql-test/tokudb_add_index/suite.opt:
  Ensure that tokudb test works even if jemalloc is not installed
storage/tokudb/mysql-test/tokudb_alter_table/suite.opt:
  Ensure that tokudb test works even if jemalloc is not installed
storage/tokudb/mysql-test/tokudb_bugs/suite.opt:
  Ensure that tokudb test works even if jemalloc is not installed
storage/tokudb/mysql-test/tokudb_mariadb/suite.opt:
  Ensure that tokudb test works even if jemalloc is not installed