VideoConfig: Ignore Borderless Fullscreen setting when the backend does not support exclusive fullscreen.

This was expected to be handled by VerifyValidity(), but that only verifies the validity of the INI files.

Source/Core/VideoCommon/VideoConfig.cpp

@@ -209,7 +209,7 @@ void VideoConfig::VerifyValidity()
 	// TODO: Check iMaxAnisotropy value
 	if (iAdapter < 0 || iAdapter > ((int)backend_info.Adapters.size() - 1)) iAdapter = 0;
 	if (iMultisampleMode < 0 || iMultisampleMode >= (int)backend_info.AAModes.size()) iMultisampleMode = 0;
-	if (!backend_info.bSupportsExclusiveFullscreen) bBorderlessFullscreen = true;
+	if (!backend_info.bSupportsExclusiveFullscreen) bBorderlessFullscreen = false;
 }
 
 void VideoConfig::Save(const std::string& ini_file)