Some tables where not eliminated when they could have been.
This was caused because HA_KEYREAD_ONLY is not set anymore for InnoDB
clustered index and the elimination code was depending on
field->part_of_key_not_clustered which was not set if HA_KEYREAD_ONLY
is not present.

Fixed by moving out field->part_of_key and
field->part_of_key_not_clustered from under HA_KEYREAD_ONLY (which
they should never have been part of).

Other things:
- Fixed a bug in make_join_select() that caused range to be used when
  there where elminiated or constant tables present (Caused wrong
  change of plans in join_outer_innodb.test). This also affected
  show_explain.test and subselct_sj_mat.test where wrong 'range's where
  replaced with index scans.

Reviewer: Sergei Petrunia <sergey@mariadb.com>