Problem was that trx->lock.was_chosen_as_wsrep_victim variable was
not set back to false after it was set true.

wsrep_thd_bf_abort
	Add assertions for correct mutex status and take necessary
	mutexes before calling thd->awake_no_mutex().

innobase_rollback_trx()
	Reset trx->lock.was_chosen_as_wsrep_victim

wsrep_abort_slave_trx()
	Removed unused function.

wsrep_innobase_kill_one_trx()
	Added function comment, removed unnecessary parameters
	and added debug assertions to enforce correct usage. Added
	more debug output to help out on error analysis.

wsrep_abort_transaction()
	Added debug assertions and removed unused variables.

trx0trx.h
	Removed assert_trx_is_free macro and replaced it with
	assert_freed() member function.

trx_create()
	Use above assert_free() and initialize wsrep variables.

trx_free()
	Use assert_free()

trx_t::commit_in_memory()
	Reset lock.was_chosen_as_wsrep_victim

trx_rollback_for_mysql()
	Reset trx->lock.was_chosen_as_wsrep_victim

Add test case galera_bf_kill