Cherry pick of global delta time from 'options-menu' branch.

Co-authored-by: Hyper <34012267+hyperbx@users.noreply.github.com>

UnleashedRecomp/app.cpp

@@ -0,0 +1,19 @@
+#include <kernel/function.h>
+#include <ui/window.h>
+#include <app.h>
+
+double g_deltaTime;
+
+// CApplication::Update
+PPC_FUNC_IMPL(__imp__sub_822C1130);
+PPC_FUNC(sub_822C1130)
+{
+    g_deltaTime = ctx.f1.f64;
+
+    SDL_PumpEvents();
+    SDL_FlushEvents(SDL_FIRSTEVENT, SDL_LASTEVENT);
+
+    Window::Update();
+
+    __imp__sub_822C1130(ctx, base);
+}