[TASK] TYPO3 code must not use the else if construct

Change "else if" into "elseif"
This is a follow-up because I forgot one "else if".

Change-Id: I51eeab3ced57a7f9ffc84ad05ee952e529ed533b
Resolves: #26295
Releases: 4.6
Reviewed-on: http://review.typo3.org/1731
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn