[BUGFIX] Wrong handling of delimiter in revExplode()

The delimiter has to be reversed for the case of limit 2,
as the search is performed on the non-reversed string.
Otherwise the function will yield different results for
limits greater than 2.

Resolves: #56405
Releases: 6.2
Change-Id: I077d38918d98fbe2e5cd153c75b115e0d95734f8
Reviewed-on: https://review.typo3.org/27926
Reviewed-by: Georg Tiefenbrunn
Tested-by: Georg Tiefenbrunn
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel