When a screen is locked, an Ebitengine application crashed as the
swap chain's Present returned DXGI_STATUS_OCCLUDED.
Let's ignore the error and continue to run the applications. In the
ideal world, an application should stop running during the screen lock,
so let's revisit this later.
This fix also fixes the issue that a Win32API GetCursorPos returned
an error ERROR_ACCESS_DENIED when the screen was locked.
Closes#2179
