Since the variable names in QShaderDescription are later compared to
QByteArrays we can gain some performance from not having to convert them
to QByteArrays later.
Task-Id: QTBUG-83706
Change-Id: Iaf80d0966f45cbb09e7c1000b7854bc488e57bb3
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>