tmf: Rework analysis-returning methods in ITmfTrace

tmf: Rework analysis-returning methods in ITmfTrace

Make the analysis accesses thread-safe: each access is now encased
in a synchronized block (or using the synchronizedMap wrapper).

This also implies exposing only Iterable's in the interface, which
is a good practice in general. If a caller could get a reference to
the map (even through unmodifiableMap), we'd have no guarantee that
they'd correctly lock their iterations, which could result in a
concurrent access error if the map is modified internally at the
same time.

Change-Id: Ibd2f1130ab9839ad20c3df3ac7c92119754ecc42
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/21152
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
IP-Clean: Matthew Khouzam <matthew.khouzam@ericsson.com>
Tested-by: Hudson CI
Reviewed-by: Genevieve Bastien <gbastien+lttng@versatic.net>