lttng: Updates to target definitions

lttng: Updates to target definitions

- Use eclipse.platform instead of SDK since we don't need JDT, PDE, etc
  This doesn't work for the 3.8 and 4.2 target because the
  org.eclipse.platform.ide product fails to start (missing splash
  screen?).
- Use cdt.dsf.gdb feature only since we don't need anything else from
  CDT
- Depend on Kepler's jdt.annotation package in the 4.4 target, to make
  sure we get 1.1.0 instead of 2.0.0 (the latter requires Java 8).
- Add license feature (to export RCP from inside Eclipse)
- Use latest Orbit repo

Change-Id: Ia5535cd054fccf2089c333828b331342d0fb434f
Signed-off-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/24744