Fixed typos
define constant only if it wasn't defined before
bug #12716 [ClassLoader] define constant only if it wasn't defined before (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

[ClassLoader] define constant only if it wasn't defined before

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

Commits
-------

388229b define constant only if it wasn't defined before
Docblock fixes
Merge branch '2.3' into 2.5

* 2.3:
  Configure firewall's kernel exception listener with configured entry point or a default entry point
  PSR-2 fixes
  [DependencyInjection] make paths relative to __DIR__ in the generated container
  Fixed the syntax of a composer.json file
  Fixed the symfony/config version constraint
  Tweaked the password-compat version constraint
  Docblock fixes
  define constant only if it wasn't defined before
  Fix incorrect spanish translation
  Fixed typos

Conflicts:
	composer.json
	src/Symfony/Bridge/Twig/TwigEngine.php
	src/Symfony/Bundle/FrameworkBundle/Controller/Controller.php
	src/Symfony/Bundle/FrameworkBundle/Templating/Loader/FilesystemLoader.php
	src/Symfony/Bundle/FrameworkBundle/composer.json
	src/Symfony/Component/Console/Descriptor/MarkdownDescriptor.php
	src/Symfony/Component/Console/Helper/TableHelper.php
	src/Symfony/Component/Console/Tests/Helper/HelperSetTest.php
	src/Symfony/Component/Debug/ErrorHandler.php
	src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
	src/Symfony/Component/Finder/Tests/Iterator/RecursiveDirectoryIteratorTest.php
	src/Symfony/Component/Form/Tests/Extension/Core/DataMapper/PropertyPathMapperTest.php
	src/Symfony/Component/HttpFoundation/Response.php
	src/Symfony/Component/HttpFoundation/StreamedResponse.php
	src/Symfony/Component/HttpKernel/Controller/ControllerResolver.php
	src/Symfony/Component/HttpKernel/Controller/ControllerResolverInterface.php
	src/Symfony/Component/HttpKernel/Debug/TraceableEventDispatcher.php
	src/Symfony/Component/HttpKernel/Fragment/RoutableFragmentRenderer.php
	src/Symfony/Component/HttpKernel/Tests/DataCollector/RequestDataCollectorTest.php
	src/Symfony/Component/Intl/NumberFormatter/NumberFormatter.php
	src/Symfony/Component/Process/Process.php
	src/Symfony/Component/Process/Tests/AbstractProcessTest.php
	src/Symfony/Component/PropertyAccess/PropertyAccessorBuilder.php
	src/Symfony/Component/Routing/Tests/Fixtures/validpattern.php
	src/Symfony/Component/Security/Http/RememberMe/TokenBasedRememberMeServices.php
	src/Symfony/Component/Security/composer.json
	src/Symfony/Component/Serializer/Encoder/XmlEncoder.php
	src/Symfony/Component/Serializer/Normalizer/GetSetMethodNormalizer.php
	src/Symfony/Component/Stopwatch/StopwatchEvent.php
	src/Symfony/Component/Stopwatch/StopwatchPeriod.php
	src/Symfony/Component/Templating/PhpEngine.php
	src/Symfony/Component/Templating/TemplateReference.php
	src/Symfony/Component/Templating/TemplateReferenceInterface.php
	src/Symfony/Component/Translation/TranslatorInterface.php
	src/Symfony/Component/Validator/ConstraintViolation.php
	src/Symfony/Component/Validator/ExecutionContextInterface.php
	src/Symfony/Component/Validator/Mapping/ClassMetadata.php
	src/Symfony/Component/Validator/MetadataFactoryInterface.php