Fix 
- bug 1217002 (RENAME/DROP crashes with innodb_track_changed_pages);
- bug 1213885 (Failing assertion: error == DB_SUCCESS in file
  handler0alter.cc line 4897 | abort in commit_cache_rebuild).

Both bugs are caused by a recent upstream change that makes
MLOG_FILE_RENAME to replay unconditionally whenever such log record is
parsed, which includes online log tracking.

Fix by
- asserting in fil_op_log_parse_or_replay() that, if a file operation
  is about to be executed, that recovery is on, and
- adjusting recv_parse_or_apply_log_rec_body() to only pass non-zero
  space_id to fil_op_log_parse_or_replay if recovery is on.  A
  non-zero space_id is what causes fil_op_log_parse_or_replay() to
  replay and not only parse the log record.

Changes for testing:
- backport from 5.5+ the debug-only innodb_log_checkpoint_now system
  variable;
- make innodb_track_changed_pages a dynamic variable, for debug builds
  only, to provide the ability to stop log tracking temporarily;
- add a new debug-only system variable innodb_track_redo_log_now, that
  issues a synchronuous redo log parse request;
- add a new debug sync point to row_merge_rename_tables();
- use all of the above to add a testcase to
  percona_changed_page_bmp_debug test.
Automerge lp:~laurynas-biveinis/percona-server/bug1217002-5.1