lock_t::requested_time: Document what the field is used for.

lock_t::wait_time: Document that the field is only used for
diagnostics and may be garbage if the system time is being adjusted.

srv_slot_t::suspend_time: Document that this is duplicating
trx_lock_t::wait_started.

lock_table_print(), lock_rec_print(): Declare in static scope.
Add a parameter for the current time.

lock_deadlock_check_and_resolve(), lock_deadlock_lock_print(),
lock_deadlock_joining_trx_print():
Add a parameter for the current time.