gitadora: add native dual fullscreen for Arena (#846)

## Link to GitHub Issue or related Pull Request, if one exists

Fixed https://github.com/spice2x/spice2x.github.io/issues/740

## Description of change

- Enable native D3D9 adapter-group dual fullscreen for the GITADORA
Arena model when the two-screen MAIN + SMALL configuration is selected
without windowed mode.
- Present MAIN and SMALL on their respective monitor heads while keeping
the invisible LEFT and RIGHT targets offscreen.
- Scope the new fake-swap-chain query behavior to the hidden GITADORA
two-head targets, preserving existing behavior for other games and
configurations.

The existing borderless-windowed two-screen path could not consistently
keep input and game timing synchronized and also reduced rendering
performance. Native dual fullscreen avoids that windowed composition
path.

## Testing

- Manually tested GITADORA Arena with separate MAIN and SMALL monitors
in fullscreen mode. Windowed mode still works if the user chooses to use
that.
- Confirmed both displays render correctly, touch input works on the
SMALL screen, gameplay input stays synchronized, and gameplay holds a
steady 60 FPS.
- Built `spicetools_spice64` at commit `e4a98e9` with the repository
Docker toolchain.
- Confirmed no new compiler warnings.
- Confirmed the forbidden static DLL import check passes.
- Confirmed the Windows 7 DLL compatibility check reports `All DLLs
OK!`.

---------

Co-authored-by: vgod <428979+vgod@users.noreply.github.com>

src/spice2x/hooks/graphics/graphics.h

@@ -119,6 +119,15 @@ extern bool D3D9_DEVICE_HOOK_DISABLE;
 
 void graphics_init();
 void graphics_hook_window(HWND hWnd, D3DPRESENT_PARAMETERS *pPresentationParameters);
+// The native GITADORA two-head D3D9 group uses the game's named SMALL
+// device window for the native physical SMALL head. The game requests
+// D3DCREATE_NOWINDOWCHANGES, so this host must be made borderless and sized
+// to the requested native SMALL mode before the native fullscreen device is
+// created. During the adapter-group startup warmup, the monitor can briefly
+// report a different mode; preserve its origin but not that temporary size.
+bool graphics_gitadora_prepare_two_head_device_window(
+    HWND hWnd, HMONITOR target_monitor = nullptr, UINT desired_width = 0,
+    UINT desired_height = 0);
 void graphics_add_wnd_proc(WNDPROC wndProc);
 void graphics_remove_wnd_proc(WNDPROC wndProc);
 void graphics_hook_subscreen_window(HWND hWnd);