Fix uint64 underflow in tick_busy_loop

[oddbookworm]

It was reported on discord that using tick_busy_loop could cause a crash in a specific scenario.

Reproducer

import pygame


WIDTH, HEIGHT = 640, 360
FPS = 60

pygame.init()
screen = pygame.display.set_mode((WIDTH, HEIGHT))
clock = pygame.Clock()

running = True
while running:
    dt = clock.tick_busy_loop(FPS) / 1000
    screen.fill("black")
    
    events = pygame.event.get()
    for event in events:
        if event.type == pygame.QUIT:
            running = False

    pygame.display.flip()

It's an odd one though, I didn't see it on my own machine. After some troubleshooting with @Matiiss and the reporter, I believe it is due to an int underflow when there is a lag spike in cpu processing, causing delay to become insanely large (thus blocking the while loop from ever finishing).

I don't think a regression test is possible with our current framework

[MyreMylar]

LGTM 👍

[Matiiss]

LGTM, the window doesn't hang anymore

[ankith26]

LGTM, thanks 🎉