[FEATURE] Use wt_spamshield old mailform on TYPO3 >= 4.6
Resolves: #50903
Releases: 6.1, 6.0, 4.7, 4.5

Change-Id: Icdbbf5396274f23486368d62ae040c9eb5e78592
Reviewed-on: https://review.typo3.org/25333
Reviewed-by: Ralf Zimmermann
Tested-by: Ralf Zimmermann