Remove macroes that was added for Qt4 compatibility

An extra-definitions of Q_DECL_OVERRIDE, QStringLiteral and Q_NULLPTR macroes
are not need anymore, since it was need previously only to Qt4 compatibility.

Change-Id: Ie773dce1606e04107fbe58f99650f30486553d8e
Reviewed-by: Sergey Belyashov <Sergey.Belyashov@gmail.com>