[rcore] Fix GetKeyPressed for PLATFORM_DESKTOP_SDL

[The-Night-Watch]

The key handling in PLATFORM_DESKTOP_SDL was faulty in two ways, which led to GetKeyPressed returning incorrect data.

CORE.Input.Keyboard.keyPressedQueue was updated only on SDL_TEXTINPUT, meaning only text characters were registered as a pressed key, but not function keys (eg. tab, backspace...).

Also on such event, both CORE.Input.Keyboard.keyPressedQueue and CORE.Input.Keyboard.charPressedQueue were assigned the key's corresponding codepoint, when CORE.Input.Keyboard.keyPressedQueue should get the raylib keycode instead.

CORE.Input.Keyboard.keyPressedQueue is now updated on SDL_KEYDOWN event instead.

[RobLoach]

How would one test this? Is there an example I couldt ry it out on?

[raysan5]

@RobLoach You need to build raylib for PLATFORM_DESKTOP_SDL but not sure if there is any example to test it properly.

@The-Night-Watch Is this change consistent with GLFW?

[The-Night-Watch]

@raysan5 Yes the idea was to align to PLATFORM_DESKTOP behavior.

@RobLoach Simplest example would be to compare the following on PLATFORM_DESKTOP and PLATFORM_DESKTOP_SDL before and after the patch:

while (!WindowShouldClose()) {
    int key = GetKeyPressed();
    int character = GetCharPressed();

    if (key) TraceLog(LOG_INFO, "key: %i", key);
    if (character) TraceLog(LOG_INFO, "char: %i", character);
    if (IsKeyPressed(KEY_BACKSPACE)) TraceLog(LOG_INFO, "backspace pressed");
}

Try typing function keys to see the issue.

[RobLoach]

Confirming that with this PR in both SDL and glfw, pressing X returns....

INFO: key: 88
INFO: char: 120

Before this PR, SDL would return...

INFO: key: 120
INFO: char: 120

Thanks!

[The-Night-Watch]

Also, before patch, pressing non text keys (eg. backspace) would lead to a false negative on IsKeyPressed(KEY_BACKSPACE) in PLATFORM_DESKTOP_SDL.

Nevermind, IsKeyPressed was actually correct.

[raysan5]

@The-Night-Watch thanks for the improvement!

@RobLoach Thanks for reviewing it!