minor #17073 [Security] skip bcrypt tests on incompatible platforms (Christian Flothmann, xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

[Security] skip bcrypt tests on incompatible platforms

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #17055
| License       | MIT
| Doc PR        |

Not all PHP versions before 5.3.7 have backported fixes that make it
possible to use `password_hash()` function. Therefore, we have to skip
tests on not supported platforms.

Commits
-------

2a6fa7b use requires annotation
65eb188 skip bcrypt tests on incompatible platforms

src/Symfony/Component/Security/Tests/Core/Encoder/BCryptPasswordEncoderTest.php

@@ -45,6 +45,9 @@ class BCryptPasswordEncoderTest extends \PHPUnit_Framework_TestCase
         }
     }
 
+    /**
+     * @requires PHP 5.3.7
+     */
     public function testResultLength()
     {
         $encoder = new BCryptPasswordEncoder(self::VALID_COST);
@@ -52,6 +55,9 @@ class BCryptPasswordEncoderTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals(60, strlen($result));
     }
 
+    /**
+     * @requires PHP 5.3.7
+     */
     public function testValidation()
     {
         $encoder = new BCryptPasswordEncoder(self::VALID_COST);
@@ -70,6 +76,9 @@ class BCryptPasswordEncoderTest extends \PHPUnit_Framework_TestCase
         $encoder->encodePassword(str_repeat('a', 73), 'salt');
     }
 
+    /**
+     * @requires PHP 5.3.7
+     */
     public function testCheckPasswordLength()
     {
         $encoder = new BCryptPasswordEncoder(self::VALID_COST);