releng: Update tycho-eclipserun to use Eclipse 4.5

releng: Update tycho-eclipserun to use Eclipse 4.5

As far as I know, there hasn't been any changes to help index format
(Apache Lucene) but it's just less dependencies to download since we are
building against Eclipse 4.5 already.

Change-Id: I41ea76eca135de50fac321a85d9e150e51f317e1
Signed-off-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/51695
Reviewed-by: Hudson CI
Reviewed-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Tested-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>