Simplify ClipCursor behaviour when RelativeMouseMode is enabled

The implementation of clip logic for relative mode seemed to
unnecessarily limit the usable area to the middle of the window, in a
2x2 pixel region. This has the adverse side effect of moving the
operating system cursor to that location, even if it is in a valid
location in the window.

While in most scenarios this is handled correctly (by storing the
original position of the cursor in the window and restoring when leaving
relative mode), there are edge cases where this clip operation can cause
WM_MOUSEMOVE to fire at a point in time where it counts as a relative
delta from SDL's perspective.

src/video/windows/SDL_windowswindow.c

@@ -992,33 +992,12 @@ WIN_UpdateClipCursor(SDL_Window *window)
 
     if ((mouse->relative_mode || (window->flags & SDL_WINDOW_MOUSE_GRABBED)) &&
         (window->flags & SDL_WINDOW_INPUT_FOCUS)) {
-        if (mouse->relative_mode && !mouse->relative_mode_warp) {
-            if (GetWindowRect(data->hwnd, &rect)) {
-                LONG cx, cy;
-
-                cx = (rect.left + rect.right) / 2;
-                cy = (rect.top + rect.bottom) / 2;
-
-                /* Make an absurdly small clip rect */
-                rect.left = cx - 1;
-                rect.right = cx + 1;
-                rect.top = cy - 1;
-                rect.bottom = cy + 1;
-
-                if (SDL_memcmp(&rect, &clipped_rect, sizeof(rect)) != 0) {
-                    if (ClipCursor(&rect)) {
-                        data->cursor_clipped_rect = rect;
-                    }
-                }
-            }
-        } else {
-            if (GetClientRect(data->hwnd, &rect) && !IsRectEmpty(&rect)) {
-                ClientToScreen(data->hwnd, (LPPOINT) & rect);
-                ClientToScreen(data->hwnd, (LPPOINT) & rect + 1);
-                if (SDL_memcmp(&rect, &clipped_rect, sizeof(rect)) != 0) {
-                    if (ClipCursor(&rect)) {
-                        data->cursor_clipped_rect = rect;
-                    }
+        if (GetClientRect(data->hwnd, &rect) && !IsRectEmpty(&rect)) {
+            ClientToScreen(data->hwnd, (LPPOINT) & rect);
+            ClientToScreen(data->hwnd, (LPPOINT) & rect + 1);
+            if (SDL_memcmp(&rect, &clipped_rect, sizeof(rect)) != 0) {
+                if (ClipCursor(&rect)) {
+                    data->cursor_clipped_rect = rect;
                 }
             }
         }