Fix possibly corrupted log clusters when using custom tab stops

The calculateTabWidth() can trigger shaping of the item, which can
cause the layout data to be reallocated, so we need to update the
local pointers to it, like we do when we explicitly invoke the
shaper.

[ChangeLog][Text] Fixed problems with text layout when using custom
tab stops.

Task-number: QTBUG-43126
Change-Id: Ifaeeeb4bfb1a55e6638b12b444f53d2679d3d1e6
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Fix constant "Qt" LOG_TAG in Android

The LOG_TAG for Android can be set by QCoreApplication::applicationName
instead of a constant "Qt" tag. This will avoid that multiple apps
will use the same tag.

Also it will be easier to filter the logs for different apps instead
of "adb logcat -s Qt" for all Qt apps.

Change-Id: I422cc3adf8b526634b5daa9a1bb1b90403de5618
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>