First see 31c6f66d9b and 5cb6e1046b.
It worked previously due to `AutomationControl::get_value`
evaluating automation, which was removed in 5cb6e1046b
in favor of properly using latency compensated evaluation.
However due to 31c6f66d9b, fader and trim automation were
never evaluated on locate, only during playback via
`Amp::setup_gain_automation`.
This fixes a case where gain is incorrect after a locate.
The amp still has the gain from before the locate, and when starting
playback ramps to the new gain.
c3d90f415c