QTreeWidget: optimize childrenCheckState

When we met at least one checked child
and at least one unchecked child
return immediately PartiallyChecked state
(no need to check other children state).

Change-Id: I17ec07a925667231a1d809695f347a0f3cfffa0e
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Add DeepBind option to QLibrary

Adds an option to request the RTLD_DEEPBIND flag to dlopen. On Linux
this can be used to force a library to resolve global symbols locally
instead of using the similarly named symbols already loaded.

This makes it possible to load and use plugins linked against Qt 4
without crashing.

[ChangeLog][QtCore][QLibrary] Added DeepBindHint which maps to RTLD_DEEPBIND
on Linux making it possible to load libraries with external symbols that
clash with already loaded ones, such as plugins linked to Qt4.

Change-Id: I4edb4af68e4a47e932a87d108360dba8d91dc34a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
tst_QItemDelegate: simplify code, no behavior change

Remove duplication of the set of flags.
Remove "text" column which had a constant value.

Change-Id: I39dd541a545664fb3f992b32b8c64e4dd263a9c7
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>