Fix softlocks from mistimed trinket text skip

You can skip the "You have found a shiny trinket!" cutscene. The
conditions are that this can only be done in the main game, in the main
dimension (no Polar Dimension), the checkpoint that you last touched
must not be in the same room as the trinket, and you have to have
skipped the Comms Relay cutscene. To do the skip, you press R on the
exact frame (or previous frame, if input delay is enabled) that Viridian
touches the trinket. Then, the gamestate will be immediately set to 0
(because of the gotoroom) and the cutscene will be skipped.

Speedrunners of the main game, well, run the main game already, the
only trinket in the Polar Dimension is not one you want to do a death
warp at, and they have a habit of automatically skipping over the Comms
Relay cutscene because they press R at the beginning of the run when
Viridian teleports to Welcome Aboard, to warp back to the Ship and so
they can leave rescuing Violet for later.

So someone reported softlocking themselves by doing the trinket text
skip in 2.3. The softlock is because they're stuck in a state where
completestop is true but can't advance to a state that turns it off. How
does this happen? It's because they pressed R too late and interrupted
the gamestate sequence. In 2.2 and previous, if you're in the gamestate
sequence then you can't press R at all, but 2.3 removes this restriction
(on account of aiming to prevent softlocks). So only on the very first
frame can you death warp and interrupt the gamestate sequence before it
happens at all.

Anyways to fix this, just turn completestop off automatically if we're
in gamestate 0 and there's no script running.

This softlock was reported by Euni on the VVVVVV speedrunning Discord.

desktop_version/src/Game.cpp

@@ -739,6 +739,7 @@ void Game::updatestate(void)
             if (!script.running)
             {
                 hascontrol = true;
+                completestop = false;
             }
             break;
         case 1: