[2.5] Remove possible call_user_func()
minor #12531 [2.5] Remove possible call_user_func() (nicolas-grekas)

This PR was merged into the 2.5 branch.

Discussion
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[2.5] Remove possible call_user_func()

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

Remove possible call_user_func() introduced in 2.5

Commits
-------

94a04cb [2.5] Remove possible call_user_func()
Merge branch '2.5' into 2.6

* 2.5:
  [Form] fixed a maxlength overring on a guessing
  [Debug] Show only unique class candidates
  [SecurityBundle] Firewall providers building - code cleaning
  [Filesystem] symlink use RealPath instead LinkTarget
  [DependencyInjection] Remove duplicate  declaration in PhpDumper
  terminals are not interactive on Travis
  Revert "[DependencyInjection] backport perf optim"
  [WebProfilerBundle] replaced pattern to path attribute in routes definitions.
  fix phpdoc's alignment
  Fixed the AuthenticationProviderInterface alignment
  Fixed the proxy-manager version constraint
  [FrameworkBundle][Template name] avoid  error message for the shortcut notation.
  [DependencyInjection] perf optim: call dirname() at most 5x
  [DependencyInjection] backport perf optim
  Fixed #12845 adding a listener to an event that is currently being dispatched will not result into a fatal error in TraceableEventDispatcher [EventDispatcher]
  [2.5] Remove possible call_user_func()
  [2.3] Remove possible call_user_func()

Conflicts:
	src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services1-1.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services1.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services11.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services12.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services8.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9.php
Merge branch '2.6' into 2.7

* 2.6: (24 commits)
  [Form] fixed a maxlength overring on a guessing
  [Debug] Show only unique class candidates
  [SecurityBundle] Firewall providers building - code cleaning
  [Filesystem] symlink use RealPath instead LinkTarget
  [DependencyInjection] Remove duplicate  declaration in PhpDumper
  terminals are not interactive on Travis
  Revert "[DependencyInjection] backport perf optim"
  [WebProfiler] Tweaked ajax requests toolbar css reset
  [WebProfilerBundle] replaced pattern to path attribute in routes definitions.
  fix phpdoc's alignment
  Fix missing addExpressionLanguageProvider (used by service container to add expression providers)
  Fixed the AuthenticationProviderInterface alignment
  Fixed the proxy-manager version constraint
  Fix missing space in label_attr
  fix DumpDataCollectorTest after CS changes
  avoid risky tests
  Fixed typo in SecurityContext PHPDoc
  [FrameworkBundle][Template name] avoid  error message for the shortcut notation.
  [DependencyInjection] perf optim: call dirname() at most 5x
  [DependencyInjection] backport perf optim
  ...