Ensure lastPixel.y is also initalized to -1 when necessary

Task-number: QTBUG-31579

Change-Id: Ia4916ac0d384ea523bbfad0dafbc90044da7ec3e
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>
Document c++11 CONFIG flag.

Task-number: QTBUG-33952
Change-Id: I752c85ba1a6d42d9794c18fb3f3198df50952c61
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>
Doc: Added external page link to "The LLDB Debugger".

-needed by an overview in qtdoc

Change-Id: I25a9b1a68de60d2ba155dbba667f4ef8054e728f
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>