fix typo in #4451

[archewashi]

I had a typo that caused the compilation to fail.

I believe it should be added because the timing of when WindowSizeCallback is called may be platform-dependent, similar to #3929.

Test case same as #4452

// Note: usage of `minshell.html` is recommended since it won't force canvas CSS overrides

#include "raylib.h"
int main(void) {
    InitWindow(800, 450, "test");
    SetTargetFPS(60);

    SetWindowState(FLAG_WINDOW_RESIZABLE);

    while (!WindowShouldClose()) {

        if (IsKeyPressed(KEY_ONE)) SetWindowSize(400, 200);

        BeginDrawing();
        ClearBackground(RAYWHITE);
        DrawText(TextFormat("window size %i x %i", GetScreenWidth(), GetScreenHeight()), 20, 20, 20, BLACK);
        EndDrawing();
    }
    CloseWindow();
    return 0;
}

[raysan5]

@asdqwe agree.