[Process] fix signal handling in wait()

wait() throws an exception when the process was terminated by a signal.
This should not happen when the termination was requested by calling
either the stop() or the signal() method (for example, inside a callback
which is passed to wait()).
[Process] Fix unit tests in sigchild environment
bug #11436 fix signal handling in wait() on calls to stop() (xabbuh, romainneutron)

This PR was merged into the 2.3 branch.

Discussion
----------

fix signal handling in wait() on calls to stop()

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11286
| License       | MIT
| Doc PR        |

``wait()`` throws an exception when the process was terminated by a signal. This should not happen when the termination was requested by calling the ``stop()`` method (for example, inside a callback which is passed to ``wait()``).

Commits
-------

5939d34 [Process] Fix unit tests in sigchild environment
eb68662 [Process] fix signal handling in wait()
94ffc4f bug #11469  [BrowserKit] Fixed server HTTP_HOST port uri conversion (bcremer, fabpot)
103fd88 [BrowserKit] refactor code and fix unquoted regex
f401ab9 Fixed server HTTP_HOST port uri conversion
045cbc5 bug #11425 Fix issue described in #11421 (Ben, ben-rosio)
f5bfa9b bug #11423 Pass a Scope instance instead of a scope name when cloning a container in the GrahpvizDumper (jakzal)
3177be5 minor #11464 [Translator] Use quote to surround invalid locale (lyrixx)
c9742ef [Translator] Use quote to surround invalid locale
4dbe0e1 bug #11120 [2.3][Process] Reduce I/O load on Windows platform (romainneutron)
797d814 bug #11342 [2.3][Form] Check if IntlDateFormatter constructor returned a valid object before using it (romainneutron)
0b5348e minor #11441 [Translator] Optimize assertLocale regexp (Jérémy Derussé)
537c39b Optimize assertLocale regexp
4cf50e8 Bring code into standard
9f4313c [Process] Add test to verify fix for issue #11421
02eb765 [Process] Fixes issue #11421
6787669 [DependencyInjection] Pass a Scope instance instead of a scope name.
9572918 bug #11411 [Validator] Backported #11410 to 2.3: Object initializers are called only once per object (webmozart)
291cbf9 [Validator] Backported #11410 to 2.3: Object initializers are called only once per object
efab884 bug #11403 [Translator][FrameworkBundle] Added @ to the list of allowed chars in Translator (takeit)
3176f8b [Translator][FrameworkBundle] Added @ to the list of allowed chars in Translator
91e32f8 bug #11381 [2.3] [Process] Use correct test for empty string in UnixPipes (whs, romainneutron)
45df2f3 minor #11397 [2.3][Process] Fix unit tests on Windows platform (romainneutron)
cec0a45 [Process] Adjust PR #11264, make it Windows compatible and fix CS
d418935 [Process] Fix unit tests on Windows platform
ff0bb01 [Process] Reduce I/O load on Windows platform
ace5a29 bumped Symfony version to 2.3.19
75e07e6 updated VERSION for 2.3.18
4a12f4d update CONTRIBUTORS for 2.3.18
98b891d updated CHANGELOG for 2.3.18
06a80fb Validate locales sets intos translator
06fc97e feature #11367 [HttpFoundation] Fix to prevent magic bytes injection in JSONP responses... (CVE-2014-4671) (Andrew Moore)
3c54659 minor #11387 [2.3] [Validator] Fix UserPassword validator translation (redstar504)
73d50ed Fix UserPassword validator translation
93a970c bug #11386 Remove Spaceless Blocks from Twig Form Templates (chrisguitarguy)
8f9ed3e Remove Spaceless Blocks from Twig Form Templates
9e1ea4a [Process] Use correct test for empty string in UnixPipes
6af3d05 [HttpFoundation] Fix to prevent magic bytes injection in JSONP responses (Prevents CVE-2014-4671)
ebf967d [Form] Check if IntlDateFormatter constructor returned a valid object before using it