buildstats-summary: Show number of packagedata tasks

:Release Notes:
Ratio of populate_sysroot tasks isn't always very accurate indicator of
sstate reuse, add packagedata tasks which show also invalidated sstate
for runtime dependencies.

:Detailed Notes:
Count tasks with both normal and setscene tasks executed as building
from scratch, if normal task had to be executed for whatever reason we
shouldn't count it as reused from sstate.

:Testing Performed:
Only build tested.

:QA Notes:
No change to image.

:Issues Addressed:
[ES-670] Improve sstate-reuse statistics

Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <martin.jansa@lge.com>

Change-Id: I425584ba6a2a63f768caa25c8e6baecc27ef977d
Reviewed-on: https://g2g.palm.com/5200
Reviewed-by: DCO Verification
Build: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Martin Jansa <Martin.Jansa@lge.com>
Tested-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Susan Montooth <susan.montooth@lge.com>