Test suite parameters for 'rocksdb' test suite were disabled in order
to get mysqld to start at all when ha_rocksdb is a dynamic plugin.

A lot of tests depend on these parameters being enabled, though. Put
them back by using the loose- form.

This change add WITH_ROCKSDB_{LZ4,BZIP2,ZSTD,snappy} CMake variables
that can be set to ON/OFF/AUTO.

If variable has default value AUTO, rocksdb links with corresponding
compression library. OFF disables compiling/linking with specific compression
library, ON forces compiling with it (cmake would throw error if library
is not available)

Support for ZLIB is added unconditionally, as it is always there.

We need to provide -fPIC for ROCKSDB files as well as -frtti if we
compile with Clang

fixed compilation, disabled unix-only tests (the ones that use bash
etc).

Changed plugin library name to ha_rocksdb.dll/so

- Put back the assert on SQL layer at the right location
- Adjust rdb_pack_with_make_sort_key to work around the assert (like
  it is done at other palaces):  MyRocks may need to pack a column
  value even when the column is not in the read set.

MyRocks seems to no longer depend on it not being present after the
merge.

- It turns out, ha_rocksdb::table_flags() can return
  HA_PRIMARY_KEY_IN_READ_INDEX for all kinds of tables (as its meaning
  is "if there is a PK, PK columns contribute to the secondary index
  tuple". There is no assumption that a certain PK column can be decoded
  from the secondary index.
  (Should probably be fixed in the upstream, too, but I was unable to
   construct a testcase showing this is necessary).

- Following the above, we can undo the init_with_fields() changes in
  table.cc. MyRocks calls init_with_fields() from ha_rocksdb::open()
  which sets index-only read capabilities properly.

mariadb_connector_c fetches all submodules in the tre.
Invoke it betfore the CONFIGURE_PLUGINS().

This is generally useful, as one can imagine many plugins have
submodules.

- Use rocksdb_sys_vars/my.cnf so that one can run tests from that suite
  by just  "./mtr rocksdb_sys_vars.$TESTNAME"
- Add rocksdb and rocksdb_sys_vars to the set of default test suites.
  Don't run with embedded server, yet.

"Userstat" feature in MariaDB does not have
I_S.table_statistics.rows_requested column.

We'll use I_S.table_statistics.rows_read instead. The testcase
doesn't do anything where rows_requested != rows_read.

MariaDB doesn't have NO_CLEAR_EVENT support in DEBUG_SYNC facility.
Luckily, the test can be re-written to use two different sync points
instead. (I've checked that the modified test fails with fb/mysql-5.6
without the fix for e004fd9f (PR #394)

- Fix the test cases to not use userstat counters specific to
  facebook/mysql-5.6
- Make testcase also check MariaDB's ICP counters
- Remove ha_rocksdb::check_index_cond(), call handler_index_cond_check
  instead.

Make rocksdb_rows_XXX counters to work

In MySQL 5.6, QUICK_SELECT_DESC calls handler->set_end_range() to
inform the storage engine about the bounds of the range being scanned.

MariaDB doesn't have that (handler::set_end_range call was back-ported
but it is not called from QUICK_SELECT_DESC).
Instead, it got prepare_*scan() methods from TokuDB.

Implement these methods so that MyRocks has information about the range
end.

- Need to manually enable userstat
- MariaDB has a lot fewer columns in table_statistics table.

and a few trivial test result updates

- rocksdb.tmpdir works (however @@rocksdb_tmpdir has no effect yet!)
- trx_info_rpl is only run in RBR mode
- type_char_indexes_collation now works
  = take into account that characters with the same weight can have
    any order after sorting (and they do in MariaDB)
  = MariaDB doesn't use index-only for extended keys that have partially-
    covered columns.

Problem:- In replication if slave has extra persistent column then these
column are not computed while applying write-set from master.

Solution:- While applying row events from server, we will generate values
for extra persistent columns.

commit f6ed777697db4ad7aee1e98c53243dced2b5891c
Author: Chenyu Yan <seayan@outlook.com>
Date:   Thu Dec 29 16:10:25 2016 -0800

    Fix BIG_TIMEOUT constant

    Summary: Update the constant to reflect what the comments indicates.

    Reviewed By: gunnarku

    Differential Revision: D4374476

    fbshipit-source-id: dd7f484

We expose @@rocksdb_skip_unique_check_tables anyway, so it's not
really disabled.

- Fix include paths, add suite.opt
- Add a test for @@rocksdb_supported_compression_types
Now all tests pass, except rocksdb_sysvars.rocksdb_rpl_skip_tx_api_basic

Deprecate the variable in MariaDB 10.2, saying
that it will be removed in 10.3.

The InnoDB source code contains quite a few references to a closed-source
hot backup tool which was originally called InnoDB Hot Backup (ibbackup)
and later incorporated in MySQL Enterprise Backup.

The open source backup tool XtraBackup uses the full database for recovery.
So, the references to UNIV_HOTBACKUP are only cluttering the source code.