lttng.ust: Replace multiple single queries by one full query

lttng.ust: Replace multiple single queries by one full query

To update data in MemoryUsageViewer, the State System would be
queried once per thread.
This patch replaces multiple single queries by a single full
state query and reads to the result.

Change-Id: I5fbb6d80a498898342db34f8278a85f02e1c6736
Signed-off-by: Loïc Prieur-Drevon <loic.prieurdrevon@gmail.com>
Signed-off-by: Alexandre Montplaisir <alexmonthy@efficios.com>
Reviewed-on: https://git.eclipse.org/r/70875
Reviewed-by: Hudson CI
Reviewed-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Tested-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>