Redirect subprocess' stdin to devnull

[rokm]

In a PyInstaller-frozen application without console (and onefile bundle), the _is_valid_exe always returns False; the subprocess.check_call() call always fails with OSError: [WinError 6] The handle is invalid because the inherited stdin handle is invalid (due to console being unavailable). Therefore, it should be redirected to devnull, like stdout and stderr are.

Also, use subprocess.DEVNULL instead of manually opening os.devnull.

Fixes part of pyinstaller/pyinstaller#6236.

[rokm]

The same redirect of stdin to devnull is also required in AdbDevice.adb_output.

[codeskyblue]

thanks

[codeskyblue]

merged in 0.11.1