QQmlMetaType: adapt to upcoming MOC format change
QQmlMetaType: adapt to upcoming MOC format change

A change is pending on qtbase that turns relatedMetaObjects into a
const pointer-to-const in order to make the relocation a read-only
one.

Adapt.

Change-Id: I503eca13c1fe80d070e3078620fa3fd5ecdef0b0
Reviewed-by: Olivier Goffart <e864599d7a41f2378eefc0011707c77a44cbfe1a@woboq.com>

mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative