query_classifier.cc:parsing_info_done: calling mysql_thread_end caused segfauls when same thread tried next time call free_embedded_thd because thread's sysvar was set to NULL in mysql_thread_end.
Added a few lines to canonical query test's input script which are not handled correctly.
Merge branch 'MAX-160' of https://github.com/skysql/MaxScale into MAX-160

Conflicts:
	query_classifier/test/canonical_tests/input.sql