decoder: update the state directly when creating an output

Threading changed, it is now possible.

This fixes the video or audio output that can render the first frames in the initial state, leading to audio/video glitches (if a delay is applied after).

For example, audio with clock-master=input:

    [00007fc4a4311760] main decoder: vlc_input_decoder_ChangeDelay():
    000055ad16120e60] main audio output error: Play in 133193
    [000055ad16120e60] main audio output error: Play in 156331
    [000055ad16120e60] main audio output error: Play in 179508
    [000055ad16120e60] main audio output error: Play in 202699
    [000055ad16120e60] main audio output error: Play in 225891
    [00007fc4a4311760] main decoder: changing delay(2): -2000000
    [000055ad16120e60] main audio output error: Play in -1750921

Refs #27918