[SECURITY] Fix RCE in swiftmailer

A remote code execution vulnerability was fixed upstream
which is now also fixed in the code we deliver with TYPO3.

This is not a full upgrade of the library but a backport
of the security fix.

Change-Id: I498163c13b09cb81c70ab7b4fa576b7a3110cbea
Resolves: #59573
Releases: 4.5, 4.6, 4.7, 6.0, 6.1, 6.2
Security-Commit: e8e192dcb778ca69746e7bd79e66aef14a12a2e2
Security-Bulletin: TYPO3-CORE-SA-2014-002
Reviewed-on: http://review.typo3.org/33458
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>