DDC-3120 - PHP 5.6 internal classes/Serializable serialization fix

[Ocramius]

See DDC-3120 ( http://www.doctrine-project.org/jira/browse/DDC-3120 )

This PR provides a backport for the 2.4 branch

[doctrinebot]

Hello,

thank you for creating this pull request. However did not open it on the "master"
branch. Our Git workflow requires all pull requests to go through "master" branch
and the release masters then merge them back into stable branches, if they are
bug fixes.

Please open the pull request again for the "master" branch and close
this one.

Nevertheless I have opened a Jira ticket for this Pull Request to track this
issue:

http://www.doctrine-project.org/jira/browse/DDC-3339

We use Jira to track the state of pull requests and the versions they got
included in.

[dbpolito]

Is there any chance this go to v2.3.x? I've tested and this change makes version v2.3.x works at php 5.6.

[Ocramius]

@dbpolito we don't even test 2.3 against PHP 5.5 and 5.6: not going to happen unless it's a security issue.

[lyrixx]

Hi @Ocramius or @beberlei ; Could you tag a new release with this fix ? Because I want to run my project on php 5.6, and this current release prevent me to do that.

[Ocramius]

This was already tagged in 2.4.6

[lyrixx]

Oups, sorry for the noise.

Github did not show me the tag for this commit: a69584a

Thanks anyway ;)

[Ocramius]

@lyrixx consider that we mark the release versions in jira.