Fix REMOTE_ADDR for cached subrequests

Fixes #7091
merged branch mweimerskirch/patch-12 (PR #7092)

This PR was submitted for the 2.2 branch but it was merged into the 2.1 branch instead (closes #7092).

Commits
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187645f Fix REMOTE_ADDR for cached subrequests

Discussion
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[HttpKernel/HttpCache] Fix "REMOTE_ADDR" for cached subrequests

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | none that I know of
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | 7091
| License       | MIT

I moved the code that modifies the REMOTE_ADDR variable further up the chain so that cached subrequests also receive the local IP address. Before, only new subrequests received the local IP address and cached ones received the original IP, which made "validateRequest" in FragmentListener fail.

Please review. I'm not sure about side-effects of this patch, including possible security issues.

Fixes #7091

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by bamarni at 2013-02-16T11:49:27Z

@fabpot rejected setting this on the master request, so you should do it on the ```forward()``` method instead.

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by mweimerskirch at 2013-02-16T12:13:46Z

@bamarni @fabpot done
[HttpKernel] added some tests for previous merge