minor #17519 remove obsolete apcu polyfill (Tobion)

This PR was merged into the 3.0 branch.

Discussion
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remove obsolete apcu polyfill

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

As @gapple pointed out in #17396

> APC is PHP <=5.4, so symfony/polyfill-apcu shouldn't be a dependency on 3.0 or master

Commits
-------

5bf64ea remove obsolete apcu polyfill

composer.json

@@ -20,8 +20,6 @@
         "doctrine/common": "~2.4",
         "twig/twig": "~1.23|~2.0",
         "psr/log": "~1.0",
-        "symfony/security-acl": "~2.7",
-        "symfony/polyfill-apcu": "~1.0,>=1.0.2",
         "symfony/polyfill-intl-icu": "~1.0",
         "symfony/polyfill-mbstring": "~1.0",
         "symfony/polyfill-php56": "~1.0",

src/Symfony/Component/ClassLoader/Tests/ApcClassLoaderTest.php

@@ -15,7 +15,7 @@ use Symfony\Component\ClassLoader\ApcClassLoader;
 use Symfony\Component\ClassLoader\ClassLoader;
 
 /**
- * @requires extension apc
+ * @requires extension apcu
  */
 class ApcClassLoaderTest extends \PHPUnit_Framework_TestCase
 {

src/Symfony/Component/ClassLoader/composer.json

@@ -17,8 +17,7 @@
     ],
     "minimum-stability": "dev",
     "require": {
-        "php": ">=5.5.9",
-        "symfony/polyfill-apcu": "~1.0,>=1.0.2"
+        "php": ">=5.5.9"
     },
     "require-dev": {
         "symfony/finder": "~2.8|~3.0"