Move QXmlReaderPrivate to private header.

First step for making QXmlSimpleReader reentrant.

Task-number: QTBUG-40015
Change-Id: I1666672b1759adb745b86ce58488142f3c66d3f5
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Make QDom/QXmlSimpleReader reentrant.

I moved the evil static bool to QXmlSimpleReaderPrivate, and used
it from QDom, when the reader instance is a QXmlSimpleReader
(if it's not, nothing happens, like before).

Task-number: QTBUG-40015
Change-Id: I54ba89db334d7b086379c4a6840cf0de23f77027
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
QPdf::addImage(): avoid a QImage detach when it's in an acceptable Format

Don't detach QImage, when it's in Format_Mono or Format_ARG32.
Use QImage::constScanLine() instead of QImage::scanLine().

Change-Id: I30fcafb576aea3189637a40fd75f77c70017ba46
Reviewed-by: John Layt <jlayt@kde.org>
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>