Fix VS2010 compile warning

warning C4510: 'QQmlPrivate::RegisterCompositeType' : default constructor could not be generated
Backport of a11f4e4318b3b9d04faf533b68809937fb2208e2 from qtdeclarative

Task-number: QTBUG-30454
Change-Id: I16ec8995ac1df3c92353006473ca082c4ed4e5b8
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>