ctf: fix performance issue with fighting optimisations

ctf: fix performance issue with fighting optimisations

The struct flatener will effectively override the byte array optimisation,
this fix will not flatten byte arrays.

Change-Id: I74d76261cc178bd4ab3fac16f749495a481ebfd3
Signed-off-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/36954
Reviewed-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Tested-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-by: Hudson CI