MDEV-6134 SUBSTRING_INDEX returns wrong result for 8bit character sets when delimiter is not found

Recording the forgotten test results.

Both bugs are caused by the same problem: the function optimize_cond() should
update the value of *cond_equal rather than the value of join->cond_equal,
because it is called not only for the WHERE condition, but for the HAVING
condition as well.

   Some lines of code in file_logger.c were lost while moving to the
   general MariaDB tree. Adding them.

    The fill_schema_table() function used to call get_table_share() for a table name in WHERE
    then clear the error list. That way plugins receive the superfluous error notification if it
    happens in it. Also the problem was that error handler didn't prevent the suppressed
    error message from logging anyway as the logging happens in THD::raise_condition
    before the handler call.
    Trigger_error_handler is remade into Warnings_only_error_handler, so it stores the error
    message in all cases in the thd->stmt_da.
    Then later the stored error is raised.

     If a prepared statement calls an stored procedure,
     the thd->server_status out of the SP goes up
     to the PS and then to the client. So that the
     client gets the SERVER_STATUS_CURSOR_EXISTS status
     if the SP uses a cursor. Which makes the embedded
     server fail.
     Fixed by saving/restoring the upper-level server_status
     in sp_head::execute().

     Thread can be disconnected internally for example after COMMIT statements.
     So we should check this for the statement execution.

    mysqltest in the 'embedded-server' mode runs queries in a separate thread,
    but it didn't do so for the prepared statements - they were run in the main thread.
    That leads to inconsistencies.
    When a test sets SESSION 'dbug' variable like
            SET SESSION debug_dbug="+d,warn_during_ha_commit_trans";
    it is run as a plain query in that separate thread, so the main thread remains unaffected.
    After that the prepared statement run in the main thread doesn't produce expected 'dbug' errors,
    so the test fails.
    To fix that I made prepared statement to be run in that special thread along with the plain queries.
    That makes the environment consistent.

  As Davi added code like
          sav_protocol= thd->protocol
          thd->protocol= &thd->protocol_binary
          ...
          thd->protocol= sav_protocol
  the fucntions like emb_store_querycache_result() cannot determine
  the used protocol testing thd->protocol == &thd->protocol_binary.
  Fixed by additional check thd->command == COM_STMT_EXECUTE.

        The function Protocol::net_store_data(a, b, CHARSET_A, CHARSET_B) should
        be adapted to be working in the embedded server as it's done
        with the Protocol::net_store_data(a, b).
        That new function renamed as net_store_data_cs, so we can make it
        virtual.

Units of subqueroes from excluded expressions should be excluded from select_lex/select_unit tree.

(and don't append --user=root for --help now, when mysqld has a fix for that)

Add test case.

Revert the old patch revid:monty@askmonty.org-20100325133339-7mkel6valai0b4lb

This patch caused the InnoDB part of the transaction to not be marked
read-write in some cases, which messes up XA commit (and likely other
stuff as well).

when converting /a/full/path/to/a/file.ext to -lfile ignore all files
with non-library extenstions.

typo in the rpm server prein scriptlet

mysql_upgrade overrode some of the custom changes made to system tables
in order to increase user name length. 
Make ALTER statements involving the affected columns take into account
length changes, as per https://mariadb.com/kb/en/create-user/#user-names

Avoid CPack complaints when a pdb file is missing for a static library
(patch from Vladislav Vaintroub)