QProcess/Win: allow child processes to change modes of the stdin pipe

To be able to call SetNamedPipeHandleState on stdin in a child
process, we must create a read-end pipe handle with the
FILE_WRITE_ATTRIBUTES flag set.
This can't be done with CreateNamedPipe but only with CreateFile.
Therefore we're creating the handles for the child process always
with CreateFile now. Besides, it's conceptually cleaner to have the
server handle of the named pipe in the calling process.

[ChangeLog][QtCore][Windows] Fix regression from Qt4 in QProcess.
It wasn't possible anymore to alter pipe modes of stdin in child
processes.

Task-number: QTBUG-35357

Change-Id: I85f09753d0c924bdc8a6cef1ea5dbe6b2299c604
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Move notification of layout change up from QApplication to QGuiApplication.

QGuiApplication-using things (like QtQuick) need to know about this, too -- this
makes QGuiApplication::setLayoutDirection actually work.

Task-number: QTBUG-21573
Change-Id: I2d2ac7dc07f11be5c7e501a3575b1d0978d8ac31
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Jan Arve Sæther <jan-arve.saether@digia.com>