- Updated slow_query_log_file_basic and general_log_file basis instead of the func version as
the func version run good but the basic versions fail.
- Sent innodb.test to dev@innodb.com.
- variables.test has differences probably due to a bug in mtr or in the SET statement (see bug#39369).
- general_log_file_basic.test and slow_query_log_file_bsaic.test have differences, which might be 
produced by the new mtr (see bug#38124).

 - fix scheduler bug

 - Rearrange spawn worker code

            returns unexpected result

If:
  1. a table has a not nullable BIT column c1 with a length
     shorter than 8 bits and some additional not nullable
     columns c2 etc, and
  2. the WHERE clause is like: (c1 = constant) AND c2 ...,
the SELECT query returns unexpected result set.


The server stores BIT columns in a tricky way to save disk
space: if column's bit length is not divisible by 8, the
server places reminder bits among the null bits at the start
of a record. The rest bytes are stored in the record itself,
and Field::ptr points to these rest bytes.

However if a bit length of the whole column is less than 8,
there are no remaining bytes, and there is nothing to store in
the record at its regular place. In this case Field::ptr points
to bytes actually occupied by the next column in a record.
If both columns (BIT and the next column) are NOT NULL,
the Field::eq function incorrectly deduces that this is the
same column, so query transformation/equal item elimination
code (see build_equal_items_for_cond) may mix these columns
and damage conditions containing references to them.

      
When switching to indexed ORDER BY we must be sure to reset the index read
flag if we are switching from a covering index to non-covering.