wined3d: Remove the OffscreenRenderingMode setting.

dlls/wined3d/adapter_gl.c

@@ -5400,10 +5400,6 @@ static BOOL wined3d_adapter_gl_init(struct wined3d_adapter_gl *adapter_gl,
     TRACE("Reporting (fake) driver version 0x%08x-0x%08x.\n",
             driver_info->version_high, driver_info->version_low);
 
-    if (wined3d_settings.offscreen_rendering_mode == ORM_BACKBUFFER)
-        ERR_(winediag)("You are using the backbuffer for offscreen rendering. "
-                "This is unsupported, and will be removed in a future version.\n");
-
     wined3d_adapter_init_fb_cfgs(adapter_gl, caps_gl_ctx.dc);
     /* We haven't found any suitable formats. This should only happen in
      * case of GDI software rendering, which is pretty useless anyway. */

dlls/wined3d/wined3d_main.c

@@ -375,9 +375,6 @@ static BOOL wined3d_dll_init(HINSTANCE hInstDLL)
             ERR_(winediag)("The GLSL shader backend has been disabled. You get to keep all the pieces if it breaks.\n");
             TRACE("Use of GL Shading Language disabled.\n");
         }
-        if (!get_config_key(hkey, appkey, env, "OffscreenRenderingMode", buffer, size)
-                && !strcmp(buffer,"backbuffer"))
-            wined3d_settings.offscreen_rendering_mode = ORM_BACKBUFFER;
         if (!get_config_key_dword(hkey, appkey, env, "VideoPciDeviceID", &tmpvalue))
         {
             int pci_device_id = tmpvalue;