[rcore] `GetFrameTime()` counts time since application was minimized

[Volcanic-Penguin]

Issue description

I'm using Raylib 5.0 with Rust but I'm presuming this is not a Rust specific bug. If it is then I'm sorry for wasting your time. If you minimize a Raylib application, when you unminimize the app, GetFrameTime() will return the total amount of time that has passed since you minimized the app. I feel like this probably shouldn't happen, anything that's moving based on frame time will move way too far when opening a minimized application, so you could probably clip through walls and stuff.

Environment

Raylib 5.0 with Rust (raylib-rs)
Windows 10
Platform backend: DESKTOP (GLFW)
Renderer: Intel(R) HD Graphics 530

Code Example

Just print GetFrameTime() to the console if it's more than one second, so something like:

if GetFrameTime() > 1.0 {
  printf(GetFrameTime());
}

[Volcanic-Penguin]

Wow well done, thanks for the fix!

That being said, I think that ideally you should be able to set FLAG_WINDOW_ALWAYS_RUN to false and still have GetFrameTime() work properly when the application stops and starts. I don't know how GetFrameTime() actually works but I could imagine maybe storing the time when the application stops and starts and subtracting that from the frame time or something like that.

[raysan5]

@asdqwe Sure! Thanks!