Replace QByteArrayData class by typedef.

Replace QByteArrayData class by typedef.

QByteArrayData was binary compatible with QArrayData, but we do not
need a separate class, QArrayData should be sufficient. Preferably we
would use QTypedArrayData<char> but it is not POD, therefore it can
not be initialized with {} syntax.

Change-Id: I1edd7b4f236b06d8f2dbfd8a37a3f5699b6a2c07
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>