Fix autotester (make it deterministic) by not using threads

[adriweb]

@jacobly0 says it's possible and Runner is angry, so gl/hf :D

[adriweb]

NTS: probably try to do what ez80sf does here: https://github.com/jacobly0/ez80sf/blob/0bd4a3307a280f81ce8ecd3544028b5fa60fb1a8/test/tester.c#L163
i.e. no emu_loop in another thread, instead just call cpu_execute in a loop manually, that we control.

From IRC:

<@jacobly> delay x milliseconds translates to execute 48000*x cycles
<@jacobly> therefore you get reproducible tests
<@Adriweb> actually yeah I guess we want to delay from the PoV of the calc, not the host
<@Adriweb> so the computer's performance doesn't really matter
<@Adriweb> and yeah, reproducible tests are the goal
<@jacobly> I mean there should be api for this
<@jacobly> which would also be useful for emscripten
<@Adriweb> indeed
<@jacobly> and my tester
<@jacobly> and linking

[adriweb]

Let's work on this sometime soon :)

[adriweb]

This is getting ridiculous, let's really work on that soon :P
When it's done, we'll also be able to enable blocking CI on the toolchain (and here eventually), that'll make PR review easier and faster.