[Console] Selectively output to STDOUT or OUTPUT stream

Addresses issues with writing console output for IBM i5 Series (OS400).
The normal QP2TERM shell outputs garbage text when attempting to write
directly to STDOUT, likely because of EBCDIC character-encoding used
on IBM platforms. Writing to the OUTPUT mimics using 'echo' or 'print'
and prints properly in the console.

Fixes #1434
merged branch johnkary/os400ConsoleBugFix (PR #4152)

Commits
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5b92b9e [Console] Selectively output to STDOUT or OUTPUT stream

Discussion
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[Console] Selectively output to STDOUT or OUTPUT stream

Originally opened in this PR targeting master, but asked to target 2.0 instead: https://github.com/symfony/symfony/pull/4148

Bug fix: yes
Feature addition: no
Backwards compatibility break: no
Symfony2 tests pass: yes
Fixes the following tickets: #1434
Todo: -

As noted in the ticket discussion and linked discussion threads, IBM i5 Series has issues with writing output to STDOUT when viewed via their QP2TERM console. The output is likely not being converted to the correct character-encoding on the system level.

This PR changes the default output stream from `php://stdout` to `php://output` for OS400 environments, which does not exhibit this issue.

I'm using `php_uname('s')` to check for the presence of "OS400", which is at least one of the IBM OS's exhibiting this issue. This check is only done once when executing a Console task and shouldn't see any adverse affects in speed on the 99% other platforms using Symfony.

I'm not a native to the OS400 platform so I can't really anticipate any other possible regressions that might occur from switching output streams for that platform. On my Mac, this change would strip all color output, but the PR code only changes output for OS400 environment. To my knowledge the QP2TERM console doesn't even support color, so no loss there.

I think this change is best to make the Console component at least usable out of the box for anyone else trying to build CLI applications for use on OS400.

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by igorw at 2012-04-29T19:41:21Z

#4146 might also need a fix for this.

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by johnkary at 2012-04-29T20:21:39Z

@igorw Hmm. In this case for #4152 when creating a CLI application, `Symfony\Component\Console\Output\ConsoleOutput` is the [default implementation](https://github.com/johnkary/symfony/blob/5b92b9ed432ea1d5f2c596517fc7f8aa825b1977/src/Symfony/Component/Console/Application.php#L113) used by `Symfony\Component\Console\Application` when not specifying your own `OutputInterface`. Our hard-coded defaults were causing problems out of the box.

I haven't looked too closely at the PRs surrounding the additions of `StreamingResponse` and your recent `OutputStream` but are we assuming anywhere that `php://stdout` is the default stream used when creating a streaming response? If so it MAY require a check similar to what I implemented for Console. My addition was only necessary because the output was being sent to a CLI console. If output is sent to a browser, I don't believe this would be an issue.

If you have something that needs testing on OS400 just ping me.