[DependencyInjection] backport perf optim

Conflicts:
	src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services11.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services19.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9.php
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_compiled.php
[DependencyInjection] perf optim: call dirname() at most 5x
Revert "[DependencyInjection] backport perf optim"

This reverts commit c11535bd6bff6d00ac5a0206e1c8d3f508bba8f3.

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/services10.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
	src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_compiled.php
bug #12855 [DependencyInjection] Perf php dumper (nicolas-grekas)

This PR was merged into the 2.3 branch.

Discussion
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[DependencyInjection] Perf php dumper

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

This PR came up after this comment to reduce the number of calls to dirname():
https://github.com/symfony/symfony/pull/12784#issuecomment-65619179

Commits
-------

375f83e Revert "[DependencyInjection] backport perf optim"
fcd8ff9 [DependencyInjection] perf optim: call dirname() at most 5x
c11535b [DependencyInjection] backport perf optim