replace call_user_func* with self invoked function

[michalbundyra]

as dev-master already use php ^7.1

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Originally posted by @samsonasik at zendframework/zend-mail#200

[michalbundyra]

I rolled back the changes on master that changed the PHP minimum, as we are not supposed to do that in a minor release. 2.10.0 will support 5.6 and 7.0 again.

As such, marking this for 3.0.0.

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Originally posted by @weierophinney at zendframework/zend-mail#200 (comment)

[michalbundyra]

This repository has been moved to laminas/laminas-mail. If you feel that this patch is still relevant, please re-open against that repository, and reference this issue. To re-open, we suggest the following workflow:

• Squash all commits in your branch (git rebase -i origin/{branch})
• Make a note of all changed files (`git diff --name-only origin/{branch}...HEAD
• Run the laminas/laminas-migration tool on the code.
• Clone laminas/laminas-mail to another directory.
• Copy the files from the second bullet point to the clone of laminas/laminas-mail.
• In your clone of laminas/laminas-mail, commit the files, push to your fork, and open the new PR.
  We will be providing tooling via laminas/laminas-migration soon to help automate the process.

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Originally posted by @weierophinney at zendframework/zend-mail#200 (comment)

[samsonasik]

i created PR #101 for it.

[samsonasik]

closing in favor of #101